Glossary | Damnosus

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11-Degree Crown: A common target crown angle that leaves a fine, even edge at the muzzle so propellant gas releases the bullet symmetrically.
5R Rifling · 5R: A rifling style with five lands cut at sloped angles and no land directly opposite another, reducing jacket deformation and fouling.

A

Accuracy vs Precision: Accuracy is hitting where you aim, precision is shots landing close together, and a rifle can show one quality without the other.
Accurize: To upgrade a factory rifle's components and fitment, such as bedding, barrel, and trigger, until it groups closer to the ceiling of its cartridge.
Ackley Improved · AI: A family of wildcat cartridges that sharpen the shoulder and reduce body taper of a parent case to gain powder capacity and longer brass life.
Action: The mechanical part of a rifle that chambers cartridges, fires, and ejects spent cases. Bolt, lever, pump, semi-auto, and break-action are the major families.
Action Wrench: A tool that clamps a rifle's action securely so a barrel can be torqued on or off without marring or twisting the receiver.
Adjustable Objective · AO: A parallax adjustment built into the scope's objective bell instead of a side-focus turret. The front ring rotates to match the target distance.
Aerodynamic Jump: A small vertical impact shift caused by the bullet's interaction with crosswind in the first few feet of flight. Measurable at extended range.
Air Gauging: A pneumatic method that measures bore diameter along a barrel's length, using airflow to verify the bore is uniform end to end.
Ammunition Lot · Lot Number: A single production run of ammunition or components; staying within one lot keeps velocity and accuracy consistent across a string.
Angle Cosine Indicator · ACI: A small device that reads the cosine of the shooting angle so a shooter can correct the drop on an uphill or downhill shot.
Angled Eyepiece: A spotting-scope eyepiece set at an angle to the body, letting a shooter view comfortably from prone or a seated position behind a tripod.
Annealing: Heating the case neck and shoulder to soften the work-hardened brass, restoring ductility, extending case life, and keeping neck tension uniform.
Anodized · Anodizing: An electro-chemical finish that grows a hard, corrosion-resistant oxide layer on aluminum. The standard surface treatment for aluminum rifle hardware.
Anti-Cant Level · Bubble Level: A small bubble level mounted on a riflescope or rail that warns a shooter when the rifle is tilted, preventing cant-induced misses at distance.
Anti-Reflection Device · ARD · Kill Flash · Honeycomb Filter: A honeycomb cap fitted over a scope's objective that breaks up glare and reflection so sunlight off the lens cannot reveal a shooter's position.
Aperture Sight · Peep Sight: A rear sight viewed through a small hole, which the eye centers automatically for precise iron-sight work at distance.
Arbor Press: A small hand press used with inline dies, popular for low-runout neck sizing and bullet seating at the bench or even at the range.
Arca Rail · Arca-Swiss: A tapered dovetail clamping standard, borrowed from camera tripods, that lets bipods and tripods slide and lock anywhere along the forend.

B

Back Pressure: The propellant gas a suppressor pushes back toward the action, which can increase fouling and disturb cycling on gas-operated rifles.
Baffle · Suppressor Baffle: An internal cone or wall inside a suppressor that slows and cools expanding muzzle gas, reducing the sound of the shot.
Baffle Strike: A bullet clipping a suppressor baffle or end cap from misalignment or a loose mount, a destructive failure that can ruin the can.
Ball and Dummy Drill: A diagnostic drill that mixes live and inert rounds at random so a flinch reveals itself on the dummy, exposing trigger faults.
Ball Powder · Spherical Powder: A spherical or flattened-ball smokeless propellant that meters smoothly through a measure but often wants a hotter primer to ignite cleanly.
Ballistic Coefficient · BC · G1 BC · G7 BC: A single number that describes how well a bullet resists air drag. Higher BC means a flatter trajectory and less wind drift downrange.
Ballistic Solver · Ballistic Calculator: Software that predicts drop and wind drift from your load, rifle, and atmospheric conditions to produce a firing solution in mils or MOA.
Ballistics: The science of projectile flight, how a bullet behaves from the moment the primer fires until it hits the target.
Barometric Pressure · Station Pressure · Absolute Pressure: The actual local air pressure fed to a ballistic solver, a key input to air density and therefore to how much drag slows the bullet in flight.
Barrel: The rifled tube that contains the burning charge, spins the bullet, and aims it. Its bore, twist, and crown set the ceiling on a rifle's accuracy.
Barrel Break-In: A shoot-and-clean routine on a new barrel meant to smooth the throat and reduce fouling; whether it actually helps is genuinely debated.
Barrel Contour · Profile · Taper: The external profile and taper of a barrel, which sets its weight, stiffness, and heat capacity by deciding how much steel surrounds the bore.
Barrel Harmonics · Barrel Whip: The vibration that travels through a barrel when a shot fires, flexing the muzzle in waves that the bullet must exit at a repeatable point.
Barrel Life: The number of accurate rounds a barrel will fire before throat erosion degrades it past acceptable precision, which varies widely by cartridge.
Barrel Nut: A threaded collar that clamps a barrel to the action and lets the smith set headspace, common on prefit and switch-barrel systems.
Barrel Shoulder: The flat face behind the tenon threads that squares the barrel against the action and sets headspace on a shouldered prefit barrel.
Barrel Tenon · Tenon: The threaded shank at the breech end of a barrel that screws into the action, cut to set headspace and align the chamber with the bolt.
Barrel Vise: A heavy clamping vise that grips the barrel while the action is torqued, the partner tool to an action wrench for barrel swaps.
Barricade · Positional Barricade: An obstacle, prop, or structure that a match stage forces you to build a shooting position around rather than firing from flat prone.
Battlesight Zero · Battle Zero: A single practical zero chosen so that aiming corrections stay small across the most common engagement distances.
BDC Reticle · Bullet Drop Compensator: A reticle or turret marked with aiming points calibrated to a specific load's drop, giving fast holdovers without dialing or doing the math.
Bearing Surface: The length of a bullet's full-diameter shank that actually contacts the bore and engages the rifling as it travels down the barrel.
Bedding: How tightly the rifle's action sits inside the stock or chassis. Glass bedding, pillar bedding, and chassis systems all aim for zero movement under recoil.
Belted Magnum · Belt: A cartridge case with a raised belt just ahead of the extractor groove that sets headspace, a defining trait of many classic magnum rounds.
Benchrest: A precision-shooting discipline using extremely stable rests, light recoil cartridges, and tuned ammunition to produce the smallest possible groups on paper.
Binocular · Binoculars · Binos: A two-eyed handheld optic for glassing terrain and spotting targets, often working alongside a spotting scope when more reach is needed at distance.
Bipod: A two-legged support that attaches to the front of the rifle, usually at a sling stud, ARCA rail, or Picatinny section.
Black Powder: The original firearm propellant, a mix of charcoal, sulfur, and saltpeter that fouls heavily and is much weaker than modern powder.
Blast Chamber: The first and largest internal chamber of a suppressor, set just ahead of the muzzle to take the initial gas blast before the baffle stack.
Blind Stage: A stage where targets and shooting positions stay concealed until the clock starts, forcing shooters to read the problem and adapt on the fly.
Blueprinting · Action Truing: Machining a rifle action's faces and threads true to spec so the barrel, bolt, and lug all seat square and concentric.
Bluing: A controlled finish that converts a steel surface to black oxide for modest corrosion resistance. The traditional treatment on blued barrels and actions.
Boat Tail: A bullet base that tapers inward toward the rear rather than cutting off flat. The taper reduces base drag and raises ballistic coefficient.
Body Die: A die that sizes the case body and bumps the shoulder back without touching the neck, useful for separating body work from neck tension control.
Bolt: The cylindrical part that closes the chamber, locks against firing pressure, and houses the firing pin and extractor in a bolt-action rifle.
Bolt Action: A rifle action operated by a manually cycled bolt: lift, pull, push, lock. It dominates precision shooting for its rigid lockup and few moving parts.
Bolt Face: The recessed front surface of the bolt that supports the case head during firing, sized to match a particular family of cartridge rims.
Bolt Gun: Slang for a bolt-action rifle, manually cycled one round at a time. Used to distinguish it from semi-autos, the "gas guns", in precision circles.
Bolt Knob: The rounded handle end the shooter grips to cycle the bolt, often oversized so it is easier to find and run quickly under stress without leaving the scope.
Bolt Shroud: The rear cap of the bolt that encloses the firing pin assembly and helps contain escaping gas if a primer or case fails.
Bolt Throw: How far the bolt handle must rotate to unlock the action, with shorter throws clearing the scope and cycling faster.
Bonded Bullet: A bullet whose jacket is chemically bonded to its lead core so the two stay together for high weight retention on game.
Bore: The inside of a rifle barrel, the channel the bullet travels down. Bore diameter is measured between the lands, not the grooves.
Bore Brush · Bronze Brush: A bristled, caliber-sized brush that threads onto a cleaning rod to scrub carbon and copper loose from the rifling.
Bore Diameter: The diameter measured across the lands, the raised ridges of the rifling, which is smaller than the groove diameter of the same barrel.
Bore Guide: A sleeve that fits the action and aligns the cleaning rod with the bore axis while keeping solvent out of the trigger and magazine.
Bore Snake · Pull-Through: A one-piece pull-through cleaning cord with an integrated brush and absorbent body, used for a quick bore wipe between strings or in the field.
Bore Solvent: A chemical cleaner that dissolves carbon and copper fouling from the bore, applied on patches and brushes between firing strings.
Borescope: A slender camera or optic that lets you inspect the inside of a barrel for fouling, erosion, and tool marks directly rather than guessing.
Boresight · Bore Sighting: A rough first alignment of the sight or scope to the bore, done before live fire to get the first shots on paper.
Bottom Metal: The underside hardware, the trigger guard plus magazine well or floor plate, that ties the action into the stock.
Box Test: A verification drill where you dial a square pattern and shoot each corner to confirm the scope tracks accurately and returns to zero.
Boxer Primer · Berdan Primer: The single-flash-hole primer design with a self-contained anvil that makes brass easy to decap and reload, unlike the twin-vent Berdan type.
Brass · Cartridge case: The metal case that holds powder, primer, and bullet together. Brass is reusable; aluminum and steel cases are typically one-shot.
Brass Life: The number of firings a cartridge case survives before necks split or the head loosens, a count that careful sizing and annealing can stretch considerably.
Brass Sorting: Grouping cases by weight or internal volume so a batch behaves consistently, reducing velocity spread for a more uniform string of shots.
Breech: The rear end of the barrel where the cartridge is loaded and sealed, opposite the muzzle. The bolt or action closes against it.
Broach Rifling: A cutting method that pulls a long, progressive multi-tooth broach through the bore, finishing every groove to full depth in a single pass.
Bull Barrel: A heavy-profile rifle barrel with little or no taper from chamber to muzzle. More mass means slower heating, more consistent harmonics.
Bullet: The projectile, just the piece that leaves the barrel. Often misused to mean the whole cartridge; that's wrong.
Bullet Base: The rear face of a bullet. Its shape, flat or tapered, is the single biggest driver of base drag and downrange ballistic coefficient.
Bullet Comparator: A caliper insert that measures to a point on the bullet ogive rather than the tip, giving repeatable cartridge length readings for seating.
Bullet Core: The inner mass of a bullet, usually lead, that supplies most of its weight; bonding it to the jacket improves weight retention on impact.
Bullet Diameter: The actual measured diameter of the bullet, matched to the barrel's groove diameter and frequently different from the cartridge's name.
Bullet Drop: How far the bullet falls below the line of sight at a given distance. Measured in inches, mils, or MOA depending on context.
Bullet Jacket: The metal skin over a bullet's core that engages the rifling and governs how the projectile behaves in flight and on the target.
Bullet Jump · Jump to Lands: The gap a bullet travels from its seated position before it engages the rifling, a distance tuned through seating depth to sharpen accuracy.
Bullet Pointing: Closing down the open tip of a match bullet in a die to sharpen the meplat and raise the ballistic coefficient for less drop and drift.
Bullet Puller · Kinetic Puller: A tool that removes a seated bullet from a loaded round so the components can be salvaged or an out-of-spec powder charge corrected.
Bullet Weight: A bullet's mass expressed in grains; heavier-for-caliber bullets raise sectional density and ballistic coefficient but need a faster twist.
Bump Gauge · Headspace Comparator: A caliper tool that measures to the case shoulder datum so a reloader can set shoulder bump and control headspace precisely.
Burn Rate: How fast a propellant converts to gas, the property that must be matched to case size and bullet weight to build pressure safely and efficiently.
Bushing Die: A sizing die that accepts interchangeable neck bushings, letting the handloader dial in an exact amount of neck tension on the bullet.
Button Rifling: A rifling method in which a hard carbide button is pushed or pulled through the bore, ironing the grooves into the steel in a single fast pass.
Buttpad · Recoil Pad: The rubber or adjustable pad at the rear of the stock that cushions recoil and sets the rifle's length of pull.

C

C.I.P. · Commission Internationale Permanente: The European standards body that sets official cartridge dimensions and pressure limits, serving as the counterpart to the American SAAMI.
Caliber: The diameter of the bullet (and the bore that fires it), traditionally expressed in inches (.308) or millimeters (6.5mm).
Caliber Designation: The naming convention used for cartridges, which often does not match true bullet diameter, as a .308 is 0.308 inch but a .38 fires a 0.357.
Caliper · Calipers: The everyday precision measuring tool of the reloading bench, reading lengths and diameters to a thousandth of an inch.
Calling the Shot: Predicting where the bullet landed from the sight picture seen at the exact instant the trigger broke, before the impact is ever spotted on target.
Cannelure: A circumferential groove rolled or cut into a bullet's jacket. Provides a crimp seat and helps lock the bullet to a specific seating depth.
Cant: Tilting the rifle left or right of vertical at the moment of the shot. At distance, even a few degrees of cant moves point of impact off the target.
Canted Base · 20 MOA Base · 30 MOA Base: A scope base machined with built-in downward slope so the elevation turret gains extra usable travel for shooting at long range.
Capped Turret: A scope turret protected by a screw-on cap, common on hunting optics that are meant to be zeroed once and then left alone in the field.
Carbon Fiber Barrel: A barrel built from a thin steel liner wrapped in carbon fiber, cutting weight and shedding heat while keeping a full-diameter profile.
Carbon Ring: A hard carbon deposit that forms at the case-mouth and throat junction, where it can raise chamber pressure and quietly spoil accuracy.
Cartridge: A complete round of ammunition: case, primer, powder, and bullet assembled together. Named after the case, not the bullet it is loaded with.
Cartridge Base to Ogive · CBTO: Distance from the cartridge base to the curve of the bullet's ogive, measured with a comparator that ignores tip variation. More repeatable than OAL.
Cartridge Overall Length · OAL · COAL: Total length of a loaded cartridge from the case base to the bullet tip. Constrained by magazine length and by how the bullet sits relative to the rifling.
Case Capacity · Water Capacity: The internal volume of a cartridge case, usually measured in grains of water, that sets how much powder it can hold and its velocity ceiling.
Case Gauge · Cartridge Gauge: A precision gauge that checks a sized case or loaded round against minimum chamber dimensions to confirm it will chamber reliably.
Case Head: The thick base of the cartridge case that holds the primer pocket and headstamp and is supported by the bolt face during firing.
Case Head Separation: A case failing where it splits at a thinned web ahead of the head, often from repeated oversizing, which can vent high-pressure gas back into the action.
Case Lube: Lubricant applied to cases before resizing so the brass slides through the die cleanly instead of sticking and seizing inside it.
Case Neck: The forward portion of a bottleneck cartridge case that grips the bullet and where tension, turning, and annealing are managed for accuracy.
Case Shoulder: The angled transition from the case body to the neck that serves as the headspacing datum on a rimless bottleneck cartridge.
Case Trimming: Cutting fired brass back to a uniform length after it stretches from firing and resizing. Keeps headspace and crimp consistent across a batch.
Case Tumbling · Wet Tumbling · Dry Tumbling: Cleaning fired brass in a tumbler, either wet with stainless pins and water or dry with a granular media, to remove fouling and residue.
Cast Bullet: A bullet poured from molten lead alloy rather than built with a copper jacket, valued for low cost and for subsonic and reduced loads.
Center-to-Center · CTC: Measuring group size as the distance between the centers of the two widest shots, the standard method for scoring a rifle's accuracy.
Centerfire: A cartridge that fires from a replaceable primer seated in a central pocket in the case head. The standard ignition system for precision rifle rounds.
Cerakote: A durable ceramic-based firearm finish that is sprayed on and oven-baked, resisting wear, corrosion, and solvents in a wide range of colors.
Chamber: The end of the bore where the cartridge sits before firing. Cut to specific cartridge dimensions. A .308 chamber will not accept a .300 PRC cartridge.
Chamber Cast: A casting poured into a rifle chamber to capture its exact internal dimensions, used to identify or verify the chambering.
Chamber Flag: A brightly colored plug inserted in the chamber to visibly show a rifle is unloaded, required at most ranges and competition stages.
Chamber Pressure: The peak pressure generated inside the cartridge case at the instant the powder burns. Measured in PSI or C.U.P.
Chamber Reamer: The precision cutting tool a gunsmith runs into a barrel blank to machine the chamber to SAAMI or custom dimensions for a given cartridge.
Chamfer: Cutting a small inside bevel on a trimmed case mouth so a bullet starts straight and seats without shaving its jacket.
Charge: The amount of powder, measured in grains, loaded into a cartridge. Each combination of cartridge + bullet + powder has a usable charge range.
Chassis · Chassis System: A rigid metal stock system the action bolts into, offering modular ergonomics and a stable, repeatable shooting platform.
Checkering: A pattern of fine cut or pressed diamonds in a grip surface that adds texture for a more secure hold. Found on stock grips and forends.
Cheek Riser · Adjustable Comb · Cheekpiece: An adjustable comb section that raises the cheek to align the eye behind a scope mounted high above the bore, giving a repeatable cheek weld.
Cheek Weld: Consistent contact of the cheek against the stock comb that repeatably places the eye behind the scope for a clear, full sight picture every shot.
Christmas Tree Reticle: A grid reticle whose windage holds branch outward and downward below center, forming a tree shape for fast hold-and-shoot corrections.
Chromatic Aberration · Color Fringing: Color fringing that appears when a lens cannot bring all wavelengths of light to the same focus, softening edges and detail in a scope image.
Chrome-Lined Bore: A barrel bore plated with hard chrome for corrosion resistance and longer service life, at a small cost to outright accuracy potential.
Chrome-Moly Steel · CrMo · 4140 · 4150: A tough chromium-molybdenum alloy steel used for rifle barrels, strong and wear-resistant but in need of a finish to guard against rust.
Chronograph · Chrono: An instrument that measures a bullet's speed, supplying the muzzle velocity and consistency numbers that feed both load tuning and the ballistic solution.
Cleaning Patch: A cloth square pushed through the bore on a jag to apply solvent and wipe loosened carbon and copper back out of the barrel.
Cleaning Rod: A one-piece coated rod that carries a jag or brush through the bore, ideally pushed breech to muzzle to protect the rifling and crown.
Click: One detent of adjustment on a scope turret. Each click moves the reticle a known angular value, typically 0.1 mil or 1/4 MOA.
CLP · Cleaner Lubricant Protectant: Cleaner, Lubricant, Protectant: a single product that loosens fouling, lubricates moving parts, and leaves a corrosion-resistant film.
CMP · Civilian Marksmanship Program: A United States program promoting marksmanship that runs service-rifle and high-power matches, training shooters in disciplined iron-sight fundamentals.
Cock on Close · Cock on Lock: An older bolt design that compresses the mainspring as the bolt is closed into battery, easing the lift required to open the action.
Cock on Open: A bolt design that cocks the firing pin as the bolt handle is lifted and the bolt opens, the standard arrangement on modern precision rifles.
Cocking Piece: The part at the rear of the striker that the sear holds and that cocks the firing pin spring as the bolt is worked.
Cold Bore Shot: The first shot fired from a cold, and often clean, barrel, which can land slightly away from the group produced once the barrel is warm and fouled.
Cold Clean Bore · CCB · First-round impact: The first shot from a clean, room-temperature barrel. Often prints slightly off from the established zero because the bore is dry of fouling.
Cold Hammer Forged · CHF · Hammer Forging: A barrel-making method in which powerful hammers forge the steel over a rifled mandrel, forming the bore and rifling in one fast, durable operation.
Comb · Stock Comb: The top edge of the buttstock where the cheek rests, which sets the shooter's eye height behind the sights and anchors a repeatable cheek weld.
Compensator: A muzzle device that vents gas upward to counter muzzle rise during firing, distinct from a brake aimed at fighting rearward recoil.
Compressed Charge: A powder load that exceeds the free space inside the case, so the bullet physically compresses the propellant as it is seated to depth.
Concentricity Gauge · Runout Gauge: A measuring tool that spins a loaded round on rollers to read how far the bullet runs out from true center, a marker of match-grade handloading.
Controlled Round Feed · CRF: A bolt design where the extractor grabs the case rim as the round leaves the magazine and holds it through the entire cycle.
Copper Fouling: Jacket metal smeared into the rifling that builds up over a string and degrades accuracy until it is cleaned out with a copper solvent.
Coriolis Effect: Apparent deflection of a bullet's flight path caused by Earth's rotation, negligible at normal precision rifle distances but measurable at ELR.
Crimp: Squeezing the case mouth inward against the seated bullet to lock it in place. Comes in roll-crimp and taper-crimp varieties.
Crimped Primer Pocket: A staked primer pocket on military brass that must be reamed or swaged before a fresh primer can be seated for reloading.
Crosswind: Wind that blows across the line of fire, the component that pushes a bullet sideways the most and forces the largest windage correction at long range.
Crown: The very end of the barrel's bore, the last surface the bullet touches as it exits, where any irregularity costs you accuracy.
Cryogenic Treatment · Cryo · Cryo Treatment: A deep sub-zero process some makers apply to barrels to relieve stress and refine the steel; the accuracy benefit is genuinely debated.
Cup and Core: The traditional bullet built from a drawn jacket cup around a swaged lead core, the basis of most match and hunting projectiles.
Custom Drag Model · CDM · Custom Curve: A bullet-specific drag curve measured from radar data, more precise than fitting a projectile to a single G1 or G7 coefficient.
Cut Rifling: The oldest rifling method, in which a single-point cutter removes metal to form one groove at a time. Slow and costly, but it leaves the bore stress-free.

D

Danger Space: The span of distance over which the bullet's path stays within target height, so a hit remains likely despite range estimation error.
Data Book · DOPE book · Rifle log: A written record of every shot fired: load, wind, atmospherics, dial settings, observed impact. The institutional memory of a rifle.
Deburring: Removing the sharp burr left on the outside of a case mouth after trimming. Usually paired with chamfering the inside edge.
Decapping · Depriming: Pushing the spent primer out of a fired case through the flash hole so the pocket can be cleaned and a fresh primer seated. The first step of reloading.
Decapping Die · Depriming Die: A reloading die whose only job is to punch the spent primer out, separate from any case sizing, so brass can be cleaned before it touches a sizing die.
Density Altitude · DA: The altitude at which the standard atmosphere would have the same air density as your current conditions. It can differ widely from elevation.
Depth of Field: The range of distances that appears in acceptable focus at the same time through a scope, a band that narrows sharply as magnification climbs.
Designated Marksman · DMR: A role and rifle class that bridges the standard rifleman and the dedicated sniper, using a magnified optic to extend reliable hits past iron-sight range.
Detachable Box Magazine · DBM · AICS Magazine: A removable box magazine, such as the AICS pattern, that swaps quickly and often allows a little more cartridge length.
Dialing · Come-Ups: Turning the elevation turret to a known drop solution for a given distance so the reticle center holds directly on the target.
Diopter · Ocular Focus: The eyepiece adjustment on a riflescope that brings the reticle into sharp focus for an individual shooter's eye.
Direct Thread · Direct-Thread Mount: A suppressor that threads straight onto the muzzle, simple and concentric but slower to swap than a quick-detach mount.
Dispersion · Cone of Fire: The spread of shots around the aim point, often pictured as a cone of fire that widens steadily with distance to the target.
Diving Board: A long forward-hanging Arca rail that extends past the forend, giving extra real estate to ride bags and barricades in field matches.
DOPE · Data On Previous Engagements · Drop chart: Pre-computed drop and wind corrections for a specific load and rifle, indexed by distance. The shooter's reference card during a string.
Doppler Radar · LabRadar: Radar that tracks a bullet through its flight to measure velocity at many points and derive a true, measured drag curve for that projectile.
Dot Drill: A fundamentals and zero-confirmation drill that fires tight groups on an array of small dots to test control and point of impact.
Dovetail: An angled, trapezoidal slot machined to hold a sight or mount by friction. An older mounting method that predates standardized rails.
Drag Coefficient · Cd: The dimensionless number describing a projectile's air resistance as a function of speed, the core quantity behind any external ballistics calculation.
Drag Model · G1 · G7 · G7 BC: The reference projectile a bullet's BC is measured against. G1 is a flat-base reference; G7 is a boat-tail reference.
Driving Band: A raised band on some solid bullets that engages the rifling while reducing bearing contact and the fouling that comes with it.
Dry Fire: Pulling the trigger on an unloaded rifle to practice trigger management, sight picture, and breath control without the cost or recoil of live ammo.
Dud: A cartridge that fails to fire when the primer is struck. Distinct from a hangfire, which fires after a delay, and a squib, which fires weakly.
Dummy Round · Dummy Cartridge: An inert cartridge with no primer or powder, used for function checks, feeding drills, and setting up reloading dies.
Duplex Reticle: A simple crosshair with thick outer posts that taper to thin lines at the center, the fast and uncluttered standard for hunting optics.

E

ED Glass · Extra-Low Dispersion · HD Glass: Extra-low dispersion optical glass that controls how light wavelengths bend, reducing color fringing for a sharper, higher-contrast image.
Effective Range: The distance at which a given rifle, cartridge, optic, and shooter combination can still produce reliable, well-placed hits.
Ejection: Throwing the fired case clear of the rifle after the extractor pulls it from the chamber. The second half of clearing the gun for the next round.
Ejector: The spring plunger or fixed blade that kicks the extracted case clear of the action once the bolt is drawn back.
Elevation: Vertical adjustment on a scope, or the up/down correction needed for distance. Dialed via the scope's top turret; runs out at the scope-elevation ceiling.
End Cap: The front cap of a suppressor, carrying the bore hole through which the bullet exits, whose alignment is critical to safety and accuracy.
Eötvös Effect · Eotvos Effect: The vertical share of the Coriolis effect: a bullet fired east strikes slightly high, one fired west strikes slightly low, because of Earth's rotation.
Erector Tube: The internal tube inside a riflescope that carries the erector lenses and reticle; turret adjustments move it, and its travel limit sets the elevation ceiling.
Exit Pupil: The cone of light leaving the scope's eyepiece. Diameter in millimeters equals the objective lens size divided by magnification.
Expander Ball: A ball on the sizing die's decapping stem that sets the neck inside diameter as the case is withdrawn, an alternative to a bushing or a separate mandrel.
Expansion · Terminal Expansion · Mushrooming: The controlled mushrooming of a bullet on impact that increases its frontal area and transfers energy into the target.
Exposed Turret · Tactical Turret: A tall, uncapped scope turret built for fast dialing of elevation and windage corrections in the field without removing a protective cover.
External Ballistics: The study of a bullet's flight from muzzle to target, covering drop, wind drift, and the aerodynamic drag that shapes the whole path.
Extractor: The hooked claw that grips the rim of a cartridge and pulls the fired case out of the chamber as the action opens.
Extreme Long Range · ELR: Shooting beyond roughly 1,500 yards as a discipline of its own, the regime where cartridge choice, scope capacity, and wind reading stop being forgiving.
Extreme Spread · ES: The difference between the fastest and slowest muzzle velocity in a string of shots. Low ES is a foundational signal of a consistent handload.
Eye Dominance · Master Eye: The tendency of one eye, the master eye, to lead in aiming, which ideally should match the shoulder a shooter mounts the rifle on.
Eye Relief: The distance between your eye and the rear scope lens at which you see the full image. Too close and the scope hits your face; too far and the image clips.
Eyebox: The three-dimensional zone behind the scope where the shooter's eye can sit and still see a full, sharp image.

F

F-Class · F-Open · F-TR: A prone, slow-fire target discipline shot with bipod and rear bag at long range, chasing the tightest possible groups on scoring rings.
Factory Ammunition · Factory Ammo: Loaded ammunition assembled and sold by a manufacturer, ready to shoot and the baseline a handloader works to match or beat.
False Shoulder: A temporary shoulder formed on a case to hold correct headspace during fireforming, keeping the case pressed against the bolt face so it fires reliably.
Fast-Focus Eyepiece: A quick-adjust ocular ring that lets a shooter sharpen the reticle to their own eye in a turn or two rather than a long threaded barrel.
Feet Per Second · fps · FPS: The standard US unit for bullet speed. A 6.5 Creedmoor load running 2,800 fps is at the typical middle of its working window.
Field Curvature: An optical flaw where the focal surface is curved rather than flat, so the center and the edges of the image will not come into sharp focus together.
Field of View · FOV: How wide an area you can see through the scope at a given distance, usually quoted in feet at 100 yards. Lower magnification = wider field of view.
Fire Lapping: Firing abrasive-coated bullets to polish a rough bore; effective at smoothing tool marks but easy to overdo, so it is used sparingly.
Fireforming: Firing a case so chamber pressure expands it to the chamber's exact shape, a routine step with wildcats and Ackley Improved designs.
Firing Pin · Striker: The spring-driven pin that strikes the primer to fire the cartridge. In most bolt rifles it is a striker carried inside the bolt.
First Focal Plane · FFP: A scope reticle that sits ahead of the erector tube. As magnification changes, the reticle scales with the image.
First-Round Hit: Landing the opening shot on target, the real measure in hunting and field work where there is no warm-up round to settle the rifle in.
First-Round Pop · FRP: A noticeably louder first shot through a suppressor, caused by oxygen trapped in the can igniting, with quieter reports on the shots that follow.
Fishtail Wind: A wind that switches back and forth near the six or twelve o'clock line, producing low deflection but proving very hard to time correctly.
Flash Hider: A muzzle device that disrupts the burning gas at the muzzle to reduce visible flash and preserve the shooter's night vision.
Flash Hole: The small hole in the bottom of a cartridge case that lets the primer's flash reach the powder. Most centerfire cases use one centered hole.
Flash Hole Uniforming: Deburring and sizing the inside of the flash hole so the primer flame reaches the powder charge the same consistent way in every case.
Floor Plate · Floorplate · Bottom Metal: The bottom of a fixed internal magazine on a bolt rifle. A hinged floor plate drops open to dump unfired rounds without cycling them through the chamber.
Fluted Barrel: A bull-profile barrel with grooves machined lengthwise along the outside. Cuts weight without giving up much stiffness, and speeds heat dissipation.
Follow-Through: Maintaining the same shooting position and sight picture through the trigger break and after the bullet has left the barrel.
Follow-Up Shot: A quick, accurate second shot that depends on recoil management and a fast bolt cycle or trigger reset to stay on target.
Foot-Pounds · ft-lbs · ft·lbf: Standard US unit of kinetic energy at the muzzle (or any specified distance). Computed from bullet weight and velocity.
Forcing Cone: The tapered transition between the chamber and the rifling, also called the throat, where the bullet first engages the lands as it enters the bore.
Forend · Forearm · Fore-end: The front portion of the stock under the barrel, where the support hand or a bipod carries the rifle's weight.
Form Factor: A number expressing how a bullet's drag compares to the standard projectile of a chosen drag model, where lower means more efficient.
Fouling: Residue left in the bore after firing, carbon from burning powder and copper from the bullet jacket. Excess fouling can open groups and shift velocity.
Fouling Shot: A shot or two fired to season a freshly cleaned bore before it settles to its normal point of impact and shoots to its established zero.
Fragmentation: A bullet breaking into multiple pieces on impact, which spreads damage across a wider area while cutting overall penetration depth.
Frangible: A bullet engineered to crumble into fine particles when it strikes a hard surface, instead of penetrating or ricocheting back.
Free Recoil: The calculated recoil energy of the rifle by itself, before the shooter's hold and body reduce the recoil that is actually felt.
Freebore: The unrifled length of bore just ahead of the case mouth that a bullet travels before the rifling engages, setting jump and usable cartridge length.
Front Sight Focus: Keeping the eye sharply focused on the front sight rather than the target, a core fundamental of accurate iron-sight shooting.
Full Metal Jacket · FMJ: A bullet whose soft lead core is fully wrapped in a harder metal jacket, leaving only the base exposed. Built to hold together and resist deformation.
Full-Length Sizing · FL Sizing: Resizing the entire fired case back toward factory spec, restoring body, shoulder, and neck for reliable chambering in any rifle.
Fullbore · Target Rifle · TR: Sling-supported iron-sight target shooting at long range, the discipline family that includes Palma and tests consistent prone marksmanship.

G

G7 Ballistic Coefficient · G7 BC: A ballistic coefficient referenced to the G7 drag model, which fits long boat-tail spitzers far better than the older G1 standard.
Gain Twist · Progressive Twist: Rifling whose twist rate accelerates from chamber to muzzle, engaging the bullet gently at first and spinning it fully by the time it exits.
Gas Check: A small metal cup crimped onto a cast bullet's base that shields the soft lead from hot propellant gas at higher velocity.
Gas Gun: Slang for a semi-automatic rifle that cycles by tapping propellant gas, most commonly an AR-platform precision rifle in the Damnosus context.
Ghillie Suit · Ghillie: A camouflage garment covered in loose strips or netting that breaks up the shooter's outline and blends them into surrounding vegetation.
Gilding Metal: The copper-zinc alloy most bullet jackets are made from, hard enough to take the rifling cleanly without heavy bore fouling.
Glass · Glass Quality: Shooter shorthand for a scope's optical quality: the clarity, contrast, and color that let you actually see and call your shots at distance.
Glass-Etched Reticle: A reticle etched directly onto a glass plate inside the scope, allowing intricate grids and clean illumination that thin wire cannot provide.
Glassing: Scanning terrain through binoculars or a spotting scope to find and identify targets or game before committing to a shot or a stalk.
Grains · gr: Unit of weight used for bullets and powder. There are 7,000 grains in a pound; a 140-grain bullet weighs about 9 grams.
Greenhill Formula: An older rule of thumb, using a constant near 150, that estimates the rifling twist needed to stabilize a bullet of a given length.
Groove Diameter: The diameter measured across the grooves of the rifling, which sets the true bullet diameter a barrel is built to shoot.
Group: A cluster of shots fired at one aiming point. Group size measures how tightly the rifle and load print, usually in inches or MOA.
Gunsmithing: The trade of building, fitting, and repairing firearms. In precision rifles it covers the machining steps that turn a factory action into a tack-driver.
Gust and Lull: The rhythmic rise and fall of wind speed, a cycle shooters use by timing their shots to a repeatable lull or a steady condition.
Gyroscopic Precession · Precession: The way a fast-spinning bullet answers a turning force by circling its nose around rather than tipping directly, letting it nose over along the trajectory.

H

Hand Lapping · Lapping · Lapped: A finishing step in which an abrasive-charged lap is worked through the bore to polish it to a uniform diameter and a smoother surface.
Hangfire: A perceptible delay between the trigger pull (and primer ignition) and the actual discharge. Range can be tenths of a second; safety implications are serious.
Head Stamp: The markings on the base of a cartridge case identifying maker, caliber, and sometimes year. The first thing to check when sorting brass.
Headspace: The dimension that determines how far a cartridge case can move forward in the chamber before its head is supported by the bolt face.
Headspace Gauge · Go Gauge · No-Go Gauge: A set of precision-ground gauges used to confirm that a chamber's headspace falls within the safe minimum and maximum limits for a cartridge.
Hearing Protection · Ear Pro: Plugs or muffs worn to guard hearing against the muzzle blast of a rifle, with extra need on guns wearing a muzzle brake.
Hex Key · Allen Key · Allen Wrench: The L-shaped hexagonal tool that turns the socket-head cap screws found on most rifle rings, bases, and rail accessories.
Hide · FFP (Final Firing Position): A concealed shooting position. In tactical and military usage, it's the spot from which the shot is taken without revealing the shooter.
High Power · Across the Course: A course-of-fire rifle discipline shot at varied distances from field positions with sling support, testing fundamentals across standing, sitting, and prone.
Holdover: Aiming with a point above the target on the reticle to compensate for bullet drop, rather than turning the elevation turret to the solution.
Holdunder: Aiming below the center of the reticle for very close shots, where the bullet still travels above the line of sight on its way to the target.
Hollow Point · HP: A bullet with a cavity at the tip. In match rifle bullets the hollow is a manufacturing artifact; in hunting bullets it is designed to expand on impact.
Horizontal Stringing: A group spread that runs side to side on the target, usually driven by changing wind, spin drift, or an inconsistent rifle cant.
Horus Reticle · H59 · Grid Reticle: A family of fine-grid holdover reticles, such as the H58, H59, and TReMoR series, that let a shooter hold drop and wind on the grid instead of dialing.
Hybrid Ogive: A nose profile that blends tangent and secant curves to reach a high ballistic coefficient while staying forgiving of how it is seated.
Hydrostatic Shock: A debated terminal effect in which a fast bullet's pressure wave is said to damage tissue beyond the physical wound channel.

I

IBS · International Benchrest Shooters: A United States benchrest governing body that runs registered matches and recognizes records across the most accuracy-driven rifle disciplines.
Illuminated Reticle: A battery-lit reticle whose aiming reference glows, aiding aim in low light or against dark and visually busy backgrounds.
Incline Shooting · Angle Shooting · Rifleman's Rule: Uphill or downhill shots drop less than the slant range implies, corrected by multiplying that range by the cosine of the angle.
Integral Suppressor: A suppressor built as a permanent part of the barrel assembly rather than a separate unit threaded onto the muzzle of a finished barrel.
Internal Ballistics: Everything that happens from primer ignition until the bullet exits the muzzle, governed by pressure, powder burn rate, and barrel behavior.
Iron Sights: Mechanical sights with no magnification: front blade or post, rear notch or aperture. The original aiming system, still carried as backup behind an optic.

J

Jacketed Hollow Point · JHP: A jacketed bullet with an open cavity at the nose, designed to expand on impact. The jacket controls expansion and protects the bore.
Jacketed Soft Point · JSP · Soft Point: A jacketed bullet with lead left exposed at the tip, giving controlled expansion that is gentler and deeper-driving than a hollow point.
Jag · Cleaning Jag: A pointed or ribbed tip that threads onto a cleaning rod and impales or grips a patch to push solvent and fouling through the bore.
Jam · Hard Jam: A seating depth that pushes the bullet into the rifling rather than leaving a gap, the opposite of jump, used to tune accuracy in some rifles.

K

Kentucky Windage: Holding off the target by eye and experience to correct for wind or drop, instead of dialing the turret or using a reticle mark.
Keyholing · Tumbling: Oval or sideways holes in paper made by an unstabilized bullet, almost always a sign of a twist rate or stability problem.
Kinetic Energy: The energy the bullet carries in flight, expressed in foot-pounds in US convention. A function of mass and the square of velocity.
King of the Mile · KO2M: An extreme-long-range steel competition where targets stretch toward and past a mile, testing equipment and the shooter at the edge of supersonic flight.
Kneeling Position: A kneeling firing position that trades some stability for a faster setup and a higher line of sight over intervening cover.

L

Lag Time: The extra time a bullet takes to reach the target compared to a drag-free vacuum, the quantity that actually drives wind drift.
Lands and Grooves: The raised ridges (lands) and recessed channels (grooves) cut spirally into the inside of a rifled barrel, which engrave the bullet and impart spin.
Lead-Free Bullet: A bullet built with no lead core, usually solid copper, used where lead is restricted or where deep, controlled penetration is wanted.
Length of Pull · LOP: The distance from the trigger to the back of the buttpad, fitted to the shooter so the rifle mounts square and the eye lands behind the scope.
Lens Coating · Multi-Coated: Thin optical films applied to scope lenses that cut surface glare and reflection, raising light transmission for a brighter, higher-contrast image.
Light Transmission: The percentage of light that passes through a scope to reach the eye, the figure that largely determines how well the optic performs in low light.
Line of Sight · LOS: The straight line from the shooter's eye through the scope reticle to the target. The bullet's path crosses this line twice on most zeros.
Load: Either the verb (the act of charging a cartridge) or the noun (a specific combination of components and charge weight).
Load Density: How completely the powder charge fills the case, expressed as a percentage, with high density near a full case generally giving more consistent ignition.
Load Development: The systematic process of testing charges and seating depths to find the most accurate, consistent handload for a specific rifle and bullet.
Load Ladder: A load development method where you shoot a series of charges in small increments, watching for accuracy nodes and pressure signs as charge weight climbs.
Loading the Bipod: Preloading slight forward pressure into the bipod legs so the rifle recoils straight back and settles its reticle near the original aiming point.
Lock Time: The brief interval between sear release and the firing pin striking the primer, where shorter timing helps a shot stay on aim.
Locking Lugs: The bolt lugs that rotate into matching recesses in the action to lock the breech closed and contain the pressure generated when a round fires.
Locking Turret: A scope turret that locks against accidental movement until the shooter deliberately releases it, guarding a setting from bumps and snags in the field.
Long Action: A rifle action sized for longer cartridges around the .30-06 length, needed when the case is too long for a short action.
Loop Sling · Shooting Sling: A sling looped around the support arm to lock the rifle tightly into the body, steadying unsupported field positions.
LPVO · Low Power Variable Optic: A low-power variable optic, such as a 1-6x or 1-8x, that runs from true 1x for close work up to mid-range magnification on the high end.
Lug Lapping: Lapping a bolt's locking lugs so both bear evenly against the action, spreading the firing load and improving shot-to-shot consistency.

M

M-LOK · MLOK: An open-source slotted attachment standard for fastening accessories directly to a forend or chassis, lighter than a full rail.
Magazine · Mag: The spring-fed container that holds cartridges and pushes them up to be stripped into the chamber. Either fixed in the rifle or a detachable box.
Magnification: How much closer a scope makes the target appear, expressed as a multiplier. A 5-25x scope ranges from 5x to 25x magnification.
Magnum: A cartridge designation indicating higher velocity, more powder capacity, or both compared to a standard parent cartridge.
Magnum Action: A rifle action lengthened and widened to feed belted and large magnum cartridges that do not fit a standard long action.
Magnum Primer: A hotter, longer-burning primer made for large cases and slow or hard-to-ignite powders, valued for reliable ignition in cold weather.
Magnus Effect: A sideways aerodynamic force on a spinning bullet flying through a crosswind that contributes to vertical deflection and adds to lateral drift.
Mammoth Sniper Challenge · Mammoth: A three-day, two-night team event at Fort Gordon where pairs ruck over 35 miles with all their gear while shooting blind long-range stages between marches.
Mandrel · Expander Mandrel: A precision rod that sets case-neck inside diameter from within, an alternative to a sizing bushing for establishing consistent neck tension.
Marginal Stability: A stability factor only slightly above the threshold, which can shave BC and open groups, with the effect strongest in cold, dense air.
Match Ammunition · Match Ammo: Factory ammunition built to tighter tolerances for accuracy, sitting between bulk loads and a fully tuned handload in performance.
Match Grade: A claim of tighter tolerances than standard production. The label carries weight only when a published spec or a real track record stands behind it.
Match Stage · Stage: One scored problem in a multi-stage match, with its own targets, shooting positions, and time limit that together define how points are scored.
Maximum Effective Range: The farthest distance at which a given rifle, load, and shooter can still produce reliable hits, the practical ceiling of the whole system.
Maximum Ordinate · Max Ordinate · Midrange Trajectory: The highest point the bullet rises above the line of sight on its arcing path out to the zero distance. Also called the midrange trajectory height.
Maximum Point Blank Range · MPBR: The farthest zero at which the bullet never rises or falls outside a chosen vital zone, so the shooter can hold dead center with no correction.
Mean Radius: The average distance of every shot in a group from the group's center, a more stable accuracy metric than a two-shot extreme spread.
Meplat: The flat or open diameter at the very tip of a bullet, whose size and uniformity influence the round's ballistic coefficient.
Meplat Trimming: Trimming bullet tips to a uniform meplat diameter so a batch flies with a more consistent ballistic coefficient, often paired with pointing.
Metallic Silhouette · Silhouette: A discipline shooting at steel animal cutouts at set distances, where each plate must be knocked fully off its stand to count for score.
Micrometer: A measuring instrument more precise than a caliper, reading to a ten-thousandth of an inch through a calibrated screw.
Mil · Milliradian · MRAD: An angular unit equal to 1/1000th of a radian, about 3.6 inches at 100 yards, or one yard at 1,000 yards. The standard unit on most precision optics.
Mil Relation Formula · Mil Ranging · Ranging Formula: The equation that converts a known target size and its measured mil subtension into distance, providing the math behind reticle-based ranging.
Mildot: An older mil-based reticle with circular dots at 1-mil intervals along the crosshair. Largely superseded by Christmas-tree and grid reticles.
Miller Stability Formula · Miller Twist Rule: A modern rule that estimates a bullet's gyroscopic stability factor from its length, diameter, weight, the barrel twist, and the muzzle velocity.
Milliradian · MRAD · Mil-Radian: An angular unit equal to one-thousandth of a radian, roughly 3.6 inches at 100 yards, used as the adjustment unit on milliradian turrets and reticles.
Mils Per Revolution: How much elevation a single full turn of a scope turret provides, which sets how many turns you need to reach a given distance.
Mini Action: A compact rifle action built around small cases like the .223, shorter and lighter than a standard short action.
Minute of Angle · MOA: An angular unit equal to 1/60th of a degree, roughly 1.047 inches at 100 yards. Most American precision optics dial in 1/4 or 1/8 MOA clicks.
Mirage: The shimmering, wavy distortion you see through a scope over hot ground or a heated barrel. It carries wind direction and speed for those who can read it.
MOA vs Mil: The two angular systems used on rifle scopes: minute of angle in inch-friendly steps, or milliradian in a base-ten metric system.
Monolithic Bullet · Solid Copper · Lead-Free: A one-piece copper or gilding-metal bullet with no separate lead core that penetrates deeply and runs long for its weight.
Monopod: A single rear leg or post under the buttstock that supplies steady elevation support for a prone shot while the bipod carries the front of the rifle.
Moving Target Hold · Mover: Using marks in the reticle to hold the correct lead on a target moving across your front, turning a swinging shot into a repeatable reference.
Muzzle: The forward end of the barrel, the opening the bullet exits through. Its surface is the crown, and it is often threaded for brakes or suppressors.
Muzzle Blast: The pressure wave and concussion released at the muzzle when a shot is fired, intensified by brakes and short barrels.
Muzzle Brake: A device threaded onto the muzzle that vents propellant gas sideways to reduce felt recoil and muzzle rise, but with added side concussion.
Muzzle Device: Any attachment threaded onto the muzzle, including brakes, compensators, flash hiders, and suppressor mounts. It redirects exiting gas to a purpose.
Muzzle Device Timing · Shim · Crush Washer: Indexing a brake or other muzzle device so its ports sit level and symmetrical, achieved with timing shims or a crush washer.
Muzzle Energy: The kinetic energy a bullet carries as it leaves the muzzle, computed from its weight and its muzzle velocity.
Muzzle Flash: The visible flash of burning gas at the muzzle when a shot is fired, reduced by a flash hider and by certain powder formulations.
Muzzle Rise · Muzzle Flip: The upward pivot of the muzzle under recoil as the rifle rotates about the shoulder, lifting the sight off target between shots.
Muzzle Threading · Thread Pitch: Threads cut on the end of the barrel, such as 5/8-24, that let a brake or suppressor mount concentric to the bore for clean bullet passage.
Muzzle Velocity · MV: How fast the bullet is moving as it exits the muzzle. Measured with a chronograph at the muzzle (or close to it).

N

NASTI · North American Sniper Team Invitational: An invitational team sniper match at Hat Creek Training where two-person military teams shoot brutal cross-canyon stages over multiple days.
Natural Point of Aim · NPOA: The direction the rifle naturally points when the shooter relaxes, with no muscle tension, just bone-on-bone support.
NBRSA · National Bench Rest Shooters Association: A United States governing body for benchrest competition, setting rules and recognizing records for the most accuracy-focused rifle discipline.
Neck Donut · Donut: A ring of thickened brass that builds at the neck-shoulder junction over repeated firings and can pinch the bullet, sometimes turned or reamed away.
Neck Sizing: Sizing only the case neck while leaving the fireformed body untouched, so the case keeps a tight custom fit to one specific chamber.
Neck Tension: The interference grip the sized case neck holds on the bullet, a key influence on how consistently each round releases and how uniform velocity stays.
Neck Turning: Shaving the case neck wall to a uniform thickness with a cutter, improving concentricity, bullet release, and clearance in tight chambers.
Necked-Down · Necked-Up: Reforming a parent case to accept a smaller (or larger) bullet diameter, one of the most common paths to a wildcat cartridge.
NFA · National Firearms Act: The US law that regulates items like suppressors and short-barreled rifles, requiring federal registration and a paid tax stamp before transfer.
Nickel-Plated Brass: Cartridge brass finished with a thin nickel plating that resists corrosion and feeds slickly, though it is harder on resizing dies.
Nitride Finish · Melonite · QPQ · Salt Bath Nitride: A surface-hardening treatment that diffuses nitrogen into steel for wear and corrosion resistance, applied to both the bore and the exterior.
Node: In load development, a velocity plateau where the rifle groups particularly well across a small spread of charge weights.
NRA · National Rifle Association: A US organization that, among other roles, writes the rules and sanctions many marksmanship competitions across rifle and pistol disciplines.
NRL · National Rifle League · NRL22: The National Rifle League, a practical precision league that includes the widely popular rimfire-based NRL22 entry series.

O

Objective Bell: The flared front housing of a riflescope that holds the objective lens, whose diameter affects light gathering and how high the scope must mount.
Objective Diameter: The width of a scope's front lens in millimeters, which governs light gathering, the exit pupil, and how high the scope must be mounted.
Objective Lens: The forward lens of a scope, the one facing the target. Its diameter in millimeters governs how much light enters.
Ocular Lens · Eyepiece: The rear lens of a riflescope, the one you look through, focused to your individual eye using the diopter adjustment in the eyepiece.
Offhand: Standing, unsupported shooting position. The rifle is held entirely by the body without bipod, sling, or rest. The hardest precision position.
Ogive: The curve of a bullet's nose, the shape between the straight bearing surface and the tip. It sets both ballistic coefficient and seating-depth measurement.
Ogive Radius · Caliber Radius Head: The radius of a bullet's nose curve expressed in calibers; a longer radius makes a sleeker point and raises ballistic coefficient.
Once-Fired Brass: Cartridge cases fired a single time, prized by handloaders as a more affordable starting point than buying new brass.
One-Piece Mount · Cantilever Mount: A single machined unit that combines the base and both rings into one rigid piece, often cantilevered forward for proper eye relief on short actions.
Open-Tip Match · OTM · OTB · Open Tip: A match bullet formed jacket-first, leaving the tip as a tiny open dimple. The construction yields the concentricity that match accuracy needs.
Optimal Barrel Time · OBT: A load-tuning theory that times the bullet's muzzle exit to a favorable point in the barrel's vibration cycle to tighten groups.
Overbore Capacity: A cartridge whose case capacity is disproportionately large relative to the bullet diameter it fires, trading high velocity for faster throat wear.
Overstabilization: Excess spin that keeps a bullet's nose from following the trajectory arc downward, which can shave a small amount of effective BC.
Overtravel: The trigger movement that continues after the sear has already released the striker, which can disturb the rifle as the shot breaks.

P

Palma · Fullbore: A sling-supported, iron-sight target discipline fired at 800, 900, and 1,000 yards, classically shot with the .308 Winchester.
Par Time: The fixed time limit a stage allows for firing the required shots, after which any rounds not yet fired are scored as misses.
Parallax: An optical effect where the reticle and the target sit on different focal planes. Moving your eye behind the scope shifts the reticle relative to the target.
Parallax Error: Aiming error that appears when the target and reticle sit on different focal planes and the eye shifts, removed by setting parallax for the range.
Parent Case: The standardized cartridge case that another cartridge or wildcat is derived from by necking, shortening, or reshaping the brass.
Parkerizing · Phosphate Finish: A phosphate conversion coating that leaves steel a matte gray-black, corrosion-resistant, and porous enough to hold protective oil.
Penetration: How deeply a bullet drives into the target, governed by its construction, weight, sectional density, and velocity at impact.
Picatinny Rail · Pic Rail · 1913 Rail: The standardized slotted mounting rail, spec MIL-STD-1913, used to attach scopes and accessories. Long-range builds use canted versions for extra elevation.
Pillar Bedding: Metal pillars set into the stock so the action screws torque against solid posts rather than compressible wood or polymer.
Point Blank Range · PBR · Maximum Point Blank Range: The distance band where the bullet's trajectory stays within a defined vertical window around the line of sight, with no holdover or dialing needed.
Point of Aim · POA: Where the reticle sits on the target at the moment of the trigger break, the intended impact location. The gap from point of impact is the shot's error.
Point of Impact · POI: Where the bullet actually lands on the target. Compared against the point of aim to evaluate the shot and to confirm a rifle's zero from a cluster.
Point-of-Impact Shift · POI Shift: A change in where a rifle prints on target when a suppressor or other muzzle device is added or removed, requiring a confirmed zero for each configuration.
Pointed Soft Point · PSP: A soft-point hunting bullet given a pointed spitzer nose to recover some of the ballistic coefficient a blunt soft point gives up.
Polygonal Rifling: A rifling profile that uses rounded hills and valleys instead of sharp lands and grooves, giving a tighter gas seal and less fouling.
Polymer Tip · Tipped Bullet · Polymer-Tipped: A plastic tip inserted in a bullet's nose that resists deformation and sharpens the meplat for a higher, more uniform ballistic coefficient.
Position Building: The deliberate process of constructing the most stable shooting position possible around whatever support and terrain are available.
Positional Shooting: Shooting from unsupported or improvised positions, such as kneeling, seated, or off a barricade, rather than from flat, stable prone.
Powder · Propellant: The propellant inside the cartridge. Burns rapidly when ignited by the primer, generating gas that pushes the bullet down the bore.
Powder Measure · Powder Thrower: A device that meters a powder charge by volume using a rotating cavity, then usually trickled up to an exact weight for precision loads.
Powder Position: Where the powder charge sits inside a partly filled case, forward against the bullet or back against the primer, which can shift ignition and velocity.
Powder Trickler: A reloading tool that dispenses powder a few kernels at a time so a charge can be brought up to an exact target weight.
Prefit Barrel · Shouldered Prefit: A pre-chambered barrel that headspaces by a shoulder or barrel nut, letting an owner swap barrels at home without a gunsmith and a lathe.
Pressure Signs: Physical clues that a load is running too hot, including flattened primers, ejector marks on the case head, and stiff bolt lift on extraction.
Primer: The shock-sensitive cup pressed into the base of a cartridge. The firing pin strikes it and its flash ignites the powder. Sized small or large.
Primer Pocket: The recess in the base of a brass case that holds the primer. Its dimensions and depth affect primer seating, ignition, and brass life.
Primer Pocket Uniforming: Cutting every primer pocket to a uniform depth with a square, flat bottom so primers seat to a consistent depth across a batch of brass.
Primer Size · Large Rifle · Small Rifle: The primer dimension a case is built to accept, large rifle or small rifle, a choice that shapes ignition behavior and sometimes load consistency.
Priming: Seating a fresh primer into the cleaned pocket of a case, the ignition step of building a handloaded cartridge.
Progressive Press: A reloading press that performs several operations per handle stroke across multiple stations, producing a finished round on each pull at high volume.
Projectile: The piece that flies: a bullet, a slug, a pellet, a sabot. "Projectile" is the umbrella; "bullet" is the specific kind for rifled barrels.
Prone: Shooting flat on the ground, rifle supported by bipod or rest. The most stable unsupported precision position.
Proof Load · Proof Round: A deliberately overpressure cartridge fired to test the strength of an action and barrel, after which the firearm receives a proof mark.
PRS · Precision Rifle Series: The Precision Rifle Series, the dominant practical precision match circuit, scored on time and hits across improvised positional stages.
Push Feed: A bolt design where the bolt pushes the round forward and the rim slips under the extractor only once the cartridge is chambered.

Q

QD · Quick Detach · Quick-Detach: Quick-detach: any mount designed to lock on and release fast by hand, used for slings, suppressors, optics, and bipods.

R

Range Card: A pre-shot reference document for a specific firing position. Lists known distances to landmarks, ranges to identified target zones.
Range Finder · Laser rangefinder · LRF: An optical device that measures the exact distance to a target using laser time-of-flight. Standard equipment for precision rifle work at unknown distances.
Rear Bag · Rear Support Bag: A small filled bag placed under the buttstock that the shooter squeezes to make fine elevation adjustments on a supported precision shot.
Rebated Boat Tail · RBT: A boat tail design with a stepped-down base behind the bearing surface, intended to ease engraving into the rifling and tune base drag.
Rebated Rim: A case design whose rim is smaller in diameter than the case body, found in families such as the .284 Winchester and the WSM cartridges.
Receiver · Action: The central housing of a rifle: it holds the bolt, locks the cartridge in place, and contains the firing mechanism. The rifle's frame of reference.
Recessed Crown · Target Crown: A crown machined below the muzzle face so the delicate rifling edge sits protected in a recess where it is shielded from dings and wear.
Recoil: The rearward push you feel when the rifle fires, the momentum of the bullet returned. Heavier rifles and muzzle brakes both reduce felt recoil.
Recoil Lug: The flange that anchors the barreled action to the stock and transfers rearward recoil force into the bedding rather than the action screws alone.
Recoil Management: Building the position and body load so the rifle recoils straight back and returns to aim, letting the shooter spot the impact of the shot.
Relative Brightness: A simple low-light index derived from the exit pupil diameter, where a larger pupil delivers a brighter image to a dark-adapted eye.
Relative Humidity: The amount of moisture in the air relative to saturation, a minor air-density input that affects bullet drop far less than most shooters expect.
Relative Long Range · RLR: Pushing any caliber to its practical ceiling, defined by your scope's elevation and your wind-read limits, not by raw distance.
Reloading · Handloading: Assembling cartridges from individual components instead of buying factory ammunition. The path to consistent precision and cheap volume.
Reloading Dies: Hardened steel cylinders that resize, deprime, and seat bullets. Each cartridge needs its own die set, typically 2-3 dies.
Reloading Press: The machine that holds the dies and applies mechanical advantage to size cases, seat bullets, and prime brass.
Reloading Scale · Beam Scale · Powder Scale: The balance, either beam or electronic, that weighs each powder charge to a tenth of a grain during precision reloading.
Remington 700 Footprint · Rem 700 Footprint: The action dimensions of the Remington 700 that became the industry pattern for stocks, bases, and aftermarket actions.
Repeater: An action fed from a magazine so successive rounds can be chambered and fired without loading each one by hand.
Respiratory Pause · Natural Respiratory Pause: The brief, still moment after a relaxed exhale when the body is calm, the natural window in which precision shooters break the shot.
Retained Energy: The kinetic energy a bullet still carries at a given distance downrange, which governs its terminal effect on game or steel.
Retained Velocity: The speed a bullet still carries downrange, which determines its remaining energy and whether it stays supersonic to the target.
Reticle: The aiming pattern inside a scope: crosshairs, dots, or marked subtensions. Mil or MOA reticles let you hold over without dialing.
Reticle Ranging: Estimating distance to a target by measuring its apparent size against the calibrated marks of a reticle, then solving with a ranging formula.
Return to Zero: The ability of a turret or mount to come back to the exact original zero after dialing a correction or removing and reattaching the optic.
Ricochet: A bullet deflecting off a hard or angled surface and continuing on an unpredictable path, a serious range-safety concern.
Rifling: The spiral grooves inside a barrel that spin the bullet for gyroscopic stability. Most precision barrels are cut, button-formed, or hammer-forged.
Rim: The flange at the base of a cartridge case. Lets the extractor grab the spent case and pull it out of the chamber.
Rimfire: A cartridge family where the primer compound is spread inside the rim of the case rather than seated in a centered cup. .22 LR is the most common example.
Rimless: A cartridge case whose rim is flush with the body and which headspaces on the shoulder, the standard design for modern bolt-action rifles.
Rimmed: A case with a flange wider than the body that headspaces on the rim, common in lever-action, break-action, and rimfire designs.
Ring Height: How tall a set of scope rings holds the optic above the receiver, setting the scope's height over bore and ensuring the bell clears the barrel.
Ring Lapping: Polishing the inner surfaces of scope rings with an abrasive lapping bar so they contact the tube evenly and grip without inducing stress.
Round Nose: A bullet with a rounded, hemispherical nose. Common in lever-action and tubular-magazine cartridges where pointed bullets can detonate primers under recoil.

S

SAAMI · Sporting Arms and Ammunition Manufacturers' Institute: The US industry body that publishes voluntary standards for cartridge dimensions, chamber drawings, and maximum pressures.
Sabot: A lightweight carrier that lets a sub-caliber projectile be fired from a larger bore, then separates and falls away at the muzzle.
Safety Selector · Safety: The control that blocks the firing mechanism to prevent an unintended discharge. On a bolt rifle, often a two- or three-position lever at the rear of the bolt.
Satterlee Test: A single-shot-per-charge velocity ladder used to find a stable charge quickly, though its small-sample statistics are debated.
SBR · Short-Barreled Rifle: A rifle with a barrel under the legal length, an NFA-regulated configuration that requires registration and a tax stamp before it can be built or owned.
Scope · Riflescope · Telescopic Sight: An optical sight with magnification and a reticle, mounted above the bore. The single biggest contributor to long-range accuracy after the shooter.
Scope Base · Mount Base: The hardware that bolts to the receiver and gives the rings a standard surface to clamp, often built with built-in cant for long-range shooting.
Scope Caps · Flip-Up Caps: Covers that protect a scope's lenses from rain, dust, and impact, then flip or pull off quickly when it is time to shoot.
Scope Elevation Ceiling: The point at which a scope's internal elevation adjustment runs out and the shooter must hold over the reticle instead of dialing.
Scope Rings: The clamps that secure a scope's main tube to the mounting base, where height, alignment, and clamping quality all affect accuracy.
Scope Shadow: The dark crescent at the edge of the image that appears when the eye is not centered behind the scope, a reliable cue to fix head position.
Sear: The surface that holds the cocked firing pin or striker until the trigger releases it, governing how clean and predictable the break feels.
Seater Die · Seating Die: The die that presses a bullet into a sized case to a set depth; competition versions use a sliding sleeve to keep the bullet aligned for low runout.
Seating Depth: How deep the bullet sits in the case neck, set by overall length or base-to-ogive, and one of the most powerful accuracy tuning variables a handloader controls.
Secant Ogive: A sharper bullet nose profile that lowers drag for a higher ballistic coefficient but is often more sensitive to seating depth and jump.
Second Focal Plane · SFP: A scope reticle that sits behind the erector tube. The reticle stays the same physical size regardless of magnification.
Second Zero · Far Zero: The farther distance at which the bullet's arc crosses the line of sight a second time, beyond the closer near zero.
Sectional Density: A bullet's weight in pounds divided by the square of its diameter in inches. Higher sectional density means more mass behind the bullet's frontal area.
Semi-Automatic · Semi-Auto · Autoloader: An action that fires one round per trigger press and uses gas or recoil energy to cycle itself, chambering the next round automatically.
Semi-Rimmed: A case design with a small rim that protrudes slightly past the body, both setting headspace and aiding extraction, between rimmed and rimless.
Service Rifle: A course of fire shot with military-pattern rifles from field positions, often fired across the course at multiple distances against time.
Set Trigger · Double-Set Trigger: A trigger that can be pre-set to break at a very light weight, found on some target rifles and traditional hunting actions.
Shell Holder: The slotted steel holder on a press ram that grips a case by its rim and holds it aligned while it is sized or has a bullet seated.
Shooter-Spotter Team: A two-person setup where one shooter fires while a partner reads wind, watches the trace, and calls corrections between shots.
Shooter's MOA · IPHY · Inch Per Hundred Yards: A rounded minute of angle treated as exactly one inch at 100 yards, which is convenient for math but drifts away from the true angular value at distance.
Shooting Bag · Support Bag · Game Changer: A filled fabric bag used to build a steady rifle support on a barricade, prop, or uneven surface in field and match shooting.
Shooting Mat: A padded mat that keeps the prone shooter off rough or wet ground for a steadier, more comfortable firing position.
Short Action: A rifle action sized for shorter cartridges around the .308 family length, lighter and quicker to cycle than a long action.
Short Magnum · WSM · SAUM: A fat, short, beltless high-capacity cartridge designed to deliver magnum performance from a compact short-action rifle.
Shot Timer: A device that signals the start of a stage and records elapsed time, central to scoring practical rifle matches that run against the clock.
Shoulder Bump: Setting the case shoulder back a few thousandths during sizing to control headspace and let the bolt close cleanly on the chambered round.
Side Focus: A parallax adjustment knob mounted on the left side of the scope, opposite the windage turret. Replaces the older adjustable objective layout.
Sight Alignment: The act of lining up the front and rear sights correctly with each other, which is the core skill behind accurate iron-sight shooting.
Sight Height · Optical Centerline Height: The vertical distance from the bore's centerline to the scope's optical centerline. Critical input to any ballistic calculator.
Sight Picture: What the shooter actually sees through the optic at the moment the trigger breaks: reticle, target, and any holds applied.
Sighters · Sighting Shots: Warm-up or practice shots permitted before a scored string so the shooter can confirm zero and current conditions.
Silencer · Suppressor · Can: A muzzle device that captures and slows propellant gas, reducing the sound signature of the shot by 25-35 decibels.
Single Shot: An action that holds one cartridge at a time and must be reloaded by hand between shots, favored in benchrest and some ELR rifles.
Single-Stage Trigger: A trigger with no take-up before the break. Pressure builds against a wall and the sear releases when the set weight is reached.
Sitting Position: A seated firing position with the elbows braced forward of the knees, offering more stability than kneeling or standing without any artificial rest.
Skim Bedding: A thin refresh layer of bedding compound applied over existing bedding to perfect the fit between action and stock.
Slant Range · Line-of-Sight Distance: The straight-line distance to a target on an incline, which is longer than the horizontal distance gravity actually acts over.
Sling: A carrying strap that doubles as a shooting aid when used in tension to stabilize the rifle in positional shooting.
Smallbore: Precision target shooting with rimfire rifles, a classic and affordable path into the core fundamentals of marksmanship and position work.
Smokeless Powder: The propellant in essentially every modern centerfire cartridge. Burns clean compared to the black powder it replaced in the late 1800s.
Snap Cap: An inert dummy cartridge sized like a live round, with no primer or powder. Used to safely dry-fire rifles whose firing pins should not strike empty.
Sniper: A marksman trained to deliver precise rifle fire at distance, paired with fieldcraft, concealment, and observation that informs much of precision-rifle gear.
Sniper's Hide Cup: A long-running two-person team precision rifle match associated with the Sniper's Hide community, built around field stages and team coordination.
Speed of Sound · Mach 1: Roughly 1,125 feet per second at sea level and varying with temperature, the speed that marks the boundary defining transonic and subsonic bullet flight.
Spherical Aberration: Image softness that appears when a lens focuses rays through its edge and its center at slightly different points, blurring fine detail across the field.
Spin Drift · Gyroscopic Drift: Lateral bullet drift caused by the gyroscopic precession of a spinning projectile. Always in the direction of the rifling twist.
Spin Rate · RPM: How fast a bullet rotates in flight, set by barrel twist and muzzle velocity, which is what drives gyroscopic stability.
Spitzer: A bullet with a pointed, conical nose. Standard nose shape for centerfire rifle bullets since the early 1900s.
Spotter: A shooting partner with a high-magnification optic whose job is to observe target impacts, read wind off mirage, and call corrections back to the shooter.
Spotting Scope: A high-magnification telescope used to observe targets at distance: read impacts, judge wind via mirage, score competitions.
Squib · Squib load: A cartridge that fires the primer but generates insufficient pressure to push the bullet out of the barrel, leaving a dangerous bore obstruction.
Stability Factor · Sg · Gyroscopic Stability: A number describing how well a barrel's spin stabilizes a bullet, where roughly 1.4 or higher is the accepted target for reliable flight.
Stainless Steel Barrel · 416R: A barrel made from corrosion-resistant stainless alloy, typically 416R, which machines cleanly and dominates precision-rifle production.
Standard Deviation · SD: A statistical measure of how tightly your shot velocities cluster around the mean. Lower SD predicts smaller vertical dispersion at distance.
Steel Safari: A field precision rifle match where shooters carry their gear and engage steel at unknown distances from natural positions, testing field skill.
Steel Target · Gong: A hardened steel plate that rings and shows a visible splash on a hit, the staple target of practical and long-range precision shooting.
Stick Powder · Extruded Powder: An extruded smokeless propellant shaped into short cylindrical rods, common in precision loads but harder to meter cleanly than spherical ball powder.
Stock: The part of the rifle the shooter holds and presses against the shoulder. Modern precision rifles increasingly use aluminum chassis instead of traditional.
Straight Pull: A bolt action cycled by pulling the handle straight back rather than lifting and rotating it, allowing very fast follow-up shots.
Stress Relieving: A controlled heat process that removes machining and forging stress so a barrel does not shift its point of impact as it heats during a string.
Sub-MOA: A rifle or load that prints groups smaller than one minute of angle, roughly one inch at one hundred yards, the common benchmark for precision.
Subsonic · sub-sonic: A load whose bullet stays below the speed of sound, roughly 1,125 fps at sea level, for its entire flight. Common in suppressed and .22 LR shooting.
Subtension: What a given division on the reticle (one mil, one MOA, one click) actually covers at a given distance. The angular value of every reticle feature.
Sunshade: A tube extension threaded onto a scope's objective that shades the front lens to cut glare and surface mirage when shooting toward bright light.
Supersonic: Faster than the speed of sound, the flight regime where most rifle bullets travel until drag slows them back toward the sound barrier.
Suppressor Cover: An insulating sleeve fitted over a suppressor that cuts the heat mirage rising off the can and shields the shooter's hands from burns.
Switch Barrel: A rifle built so barrels swap quickly to change caliber or replace a worn tube while holding zero and correct headspace.

T

Take-Up · Slack: The light initial travel before the trigger reaches the wall, the defining first stage of a two-stage precision trigger.
Tall Target Test: A measured vertical dialing test that confirms whether a scope's clicks deliver their stated value, catching small tracking errors over a long travel.
Tangent Ogive: A bullet nose profile whose curve blends smoothly into the shank, giving a forgiving design that tolerates a wide range of bullet jump.
Taper Crimp: A light crimp that squeezes the case mouth straight inward without rolling it over, used where neck tension alone will not hold the bullet.
Target Lead · Lead: Aiming ahead of a moving target so the bullet and the target arrive at the same point at the same instant. It grows with target speed and time of flight.
Tax Stamp: The federal tax-paid approval required to own an NFA item such as a suppressor, documenting that the transfer tax has been paid and the transfer cleared.
Temperature-Stable Powder · Temp-Insensitive Powder: Smokeless propellant formulated so that velocity barely shifts between hot and cold conditions, keeping a load's drop consistent year-round.
Terminal Ballistics: The study of how a bullet behaves on and inside the target, including penetration, expansion, and the energy it delivers on impact.
Terminal Velocity · Impact Velocity: The speed a bullet still carries when it reaches the target, the figure that sets impact energy and how the bullet behaves on arrival.
The Brutality: A match that pairs a physically punishing ruck or fitness challenge with precision rifle stages, testing both endurance and marksmanship under fatigue.
Thermals · Updraft: Vertical air currents rising off heated terrain or sinking off cooled terrain, capable of lifting or dropping a long-range shot.
Thread Protector: A small cap that screws over a threaded muzzle to guard the threads and crown when no brake, flash hider, or suppressor is mounted.
Throat · Leade: The short unrifled or partly rifled section just ahead of the chamber where the bullet first meets the rifling as the round fires.
Throat Erosion: The gradual wearing-forward of the throat under repeated heat and pressure, which moves the rifling away and slowly degrades a barrel's accuracy.
Throw Lever · Cattail: A lever attached to a riflescope's magnification ring that allows fast, glove-friendly power changes with a single hand.
Time of Flight · TOF: The elapsed time a bullet spends in the air to the target, the quantity that underlies both drop and wind drift at any range.
Torque Driver · FAT Wrench · Torque Wrench: A handheld tool that tightens fasteners to an exact, repeatable torque, used on rings, bases, and action screws to protect zero and grouping.
Torque Spec · Inch-Pounds: The manufacturer's recommended tightening force for ring and base screws, applied with a calibrated torque wrench in inch-pounds for repeatable mounting.
Trace · Vapor trail: The visible streak of disturbed air a bullet leaves behind in flight. Visible through a spotting scope under the right light conditions.
Trajectory: The arc a bullet follows from the moment it leaves the muzzle until it hits the target. Gravity bends it downward; wind pushes it sideways.
Transonic · Transonic Range: The speed band around the sound barrier, roughly Mach 1.2 down to 0.8, where shifting airflow can disturb a bullet's flight.
TReMoR3 · TREMOR3 · Tremor 3: A Horus Vision grid reticle by Todd Hodnett, adopted by USSOCOM, that lets shooters hold drop, wind, and lead corrections instead of dialing.
Trigger: The mechanism the shooter operates to release the sear and fire the rifle. Light, crisp, and predictable beats every other characteristic.
Trigger Control · Trigger Press: Pressing the trigger straight to the rear with steady, isolated finger pressure so the shot breaks without disturbing the aligned sight picture.
Trigger Creep · Creep: Unwanted trigger movement after the wall and before the break, felt as a mushy drag that makes the moment of release hard to predict.
Trigger Pin: The small cross pin the trigger pivots on inside the action or trigger housing. A wear and fitment point in any trigger group.
Trigger Pull: The act of operating the trigger, the shooter's technique rather than the rifle's setting. Done well, the break barely disturbs the sight picture.
Trigger Reset: The forward distance the trigger must travel after firing before the sear re-engages and the trigger is ready to fire the next shot.
Trigger Weight: The amount of force required to break the trigger and fire the rifle, measured in ounces or pounds. Precision rifles typically run 1.5-3 lb.
Tripod · Tripod Shooting: A three-legged support that stabilizes the rifle for standing or seated shots, usually clamping the rifle at an Arca interface on the forend.
Tripod Head · Ball Head · Leveling Head: The adjustable head atop a tripod that aims, locks, and levels the mounted rifle, optic, or spotting scope, setting how steady the position holds.
True MOA: The exact value of a minute of angle, roughly 1.047 inches at 100 yards, rather than the convenient rounded inch that many shooters use instead.
Truing: Adjusting the inputs to a ballistic calculator until predicted impact matches observed impact at distance. Calibrates the model to the rifle.
Tube Diameter · 30mm · 34mm · Main Tube: The diameter of a riflescope's main body; larger tubes generally allow more internal adjustment travel and require matching rings to mount correctly.
Turret · Tactical Turret · Capped Turret: An adjustment knob on the scope, typically one for elevation (top) and one for windage (right). Used to move the reticle relative to the bore.
Turret Press: A reloading press with a rotating die head that holds all dies mounted at once, so each step runs in turn without swapping dies between operations.
Turret Revolution · Second Rotation: One full turn of an elevation turret; distant targets can demand more than one, where a zero stop helps the shooter track which rotation they are on.
Turret Tracking · Tracking: How faithfully a scope's actual point-of-impact movement matches the values dialed on its turrets, the core measure of a scope's mechanical honesty.
Twilight Factor: A figure derived from objective diameter and magnification that estimates how well a scope resolves fine detail in low light.
Twist Direction · Right-Hand Twist · Left-Hand Twist: Whether the rifling spins the bullet clockwise or counter-clockwise, which sets the direction the bullet drifts laterally in flight.
Twist Rate: The distance, in inches, a bullet travels through the barrel for one full rotation. Written as 1:N. A 1:8 twist makes one full rotation every 8 inches.
Two-Stage Trigger: A trigger with a deliberate first stage of light take-up that stops at a wall, then a defined second stage that breaks the shot.

U

Unknown Distance · UKD: A stage or match format where target ranges are not given and the shooter must determine them before firing, testing ranging skill alongside marksmanship.

V

Velocity: How fast the bullet is moving, measured in feet per second. Muzzle velocity is the speed at the muzzle; downrange velocity is what matters for the hit.
Velocity Flat Spot · Flat Spot: A charge-weight range where measured muzzle velocity barely changes, which some handloaders read as a stable accuracy node.
Velocity Truing: Adjusting the muzzle velocity or BC in a ballistic solver until its predictions match your real impacts at distance.
Vertical Stringing: A group spread that runs up and down on the target, most often pointing to velocity variation or an inconsistent shooting position.
Vignetting: A darkening at the edges of the sight picture, usually caused by short eye relief or an off-center eye blocking part of the light cone.
Virgin Brass: Unfired new cartridge cases, which usually benefit from a light prep pass and may need one firing to settle into the chamber.
VLD Bullet · Very Low Drag: A long, sharp-nosed boat-tail match or hunting bullet built around a secant ogive to maximize ballistic coefficient at long range.

W

Wadcutter · WC: A flat-nosed bullet that cuts a clean, scoreable hole in paper targets. Common in target pistol; rare in centerfire rifle.
Weaver · Weaver Base: An older cross-slot mounting standard with narrow, irregularly spaced slots, the forerunner that the more uniform Picatinny system later superseded.
Weight Retention: The share of a bullet's original mass that stays intact after impact, a key measure of how a hunting bullet performs in the target.
Wildcat Cartridge · Wildcat: A nonstandardized cartridge created by reforming or modifying an existing parent case rather than one made to an industry specification.
Wind Bracket · Bracketing: Holding for the middle of a likely wind range, then accepting the resulting horizontal spread when the wind call is genuinely uncertain.
Wind Flags: Downrange flags or indicators that reveal wind speed and direction at points along the bullet's path to the target.
Wind Gradient: The change in wind speed with height above the ground or across terrain, meaning the wind at the target can differ from the wind at the muzzle.
Wind Hold vs Wind Dial: Two ways to correct for wind. Hold means leaving the turret alone and aiming the reticle into the wind by a measured amount.
Wind Meter · Kestrel · Anemometer: A handheld weather meter that reads wind speed, temperature, and pressure at the firing line to feed a ballistic solver and refine a firing solution.
Wind Reading · Wind Call: The skill of judging wind speed, direction, and value to convert it into an accurate horizontal correction, the hardest part of long-range shooting.
Wind Value · Full Value · Half Value: The clock-based fraction of the wind that actually pushes a bullet sideways, ranging from full value across the line of fire to zero straight on.
Windage: Horizontal adjustment on a scope, or the sideways correction needed for a wind reading. "10 mils right" means hold or dial 10 mil for a left-to-right wind.
Wobble Zone · Arc of Movement: The small area the reticle drifts across on the target from the shooter's own movement, breathing, and pulse while holding aim.

Y

Yaw of Repose: The small steady tilt a spinning bullet holds relative to its flight path, the aerodynamic cause of spin drift at long range.

Z

Zero: The distance at which your scope's reticle and the bullet's flight path coincide. "100-yard zero" means the bullet hits exactly where the crosshair is at 100.
Zero Distance: The specific range at which the scope is zeroed, where bullet impact aligns with the reticle's main crosshair.
Zero Stop: A mechanical feature on an elevation turret that lets a shooter spin back down to the rifle's zero by feel, without overshooting it.
Zoom Ratio · Erector Ratio: The ratio between a scope's highest and lowest magnification, where a 5-25x optic offers a five times zoom range that drives versatility and cost.