A ladder test finds the powder charges your rifle sends to the same height on a target, and it works by reading the shots at a distance where small velocity differences have room to show themselves. You fire one round at each charge in a climbing series, all at one aiming point, and measure how high each impact sits. Charges that stack level with each other are the ones to look at harder.
It is also the easiest load development method to misread. A single shot at each charge is a sample of one, and wind at 600 yards moves impacts up and down as well as sideways. This is a guide to what a ladder test is, how to load and shoot one at distance, how to read vertical on the target, how to keep wind out of the answer, and where the method runs out of road without more rounds.
What a ladder test is, and where it came from
A ladder test is a load ladder fired at long range with one round per charge weight, in a rising series, at a single aiming mark. The name attaches to Creighton Audette, the highpower competitor who worked the method out, which is why you will see it called the Audette ladder. Each round in the string is one rung. Nothing about the rifle changes between shots, and that is the entire design, because the only variable is the powder charge and any vertical difference on paper traces back to it.
The rule that makes the test work is that you never touch the turrets. You hold the exact same point of aim for every shot in the string, so the target itself becomes the measuring stick.1 Adjust the scope mid-string and the data is gone, since a turret click and a charge effect now look identical on paper.
What you are hunting for is a node, a run of consecutive charges whose impacts land at nearly the same elevation. Three or four rungs in a row printing at one height suggest a charge window where a small error in powder weight produces a small error on target. That is the traditional claim, at least. The back half of this guide deals with how much a single ladder can actually support it.
Why the ladder needs distance
Distance is what makes a ladder readable at all. A charge that adds twenty feet per second of muzzle velocity lifts the impact slightly, and how much it lifts depends almost entirely on how long the bullet stays in the air. Flight time is the lever here, and it grows a good deal faster than range does.
It helps to put real numbers against that. Hornady's 147 grain ELD Match leaves a 6.5 Creedmoor at about 2,695 feet per second and reaches 100 yards in roughly 0.11 seconds, while 600 yards takes about 0.76 seconds, close to seven times longer. Drop grows with the square of flight time, so the vertical gap between two neighboring charges opens up far wider downrange than it ever does at 100. Up close, two charges separated by a few tens of feet per second can print inside the same ragged hole, and no amount of careful measuring pulls them back apart.
Practitioners of the method put the floor at about 300 yards, calling that the minimum distance for using the ladder effectively.2 A genuine sweet spot can surface in long-range shooting that would never have been apparent from 100 yard targets or from chronograph data alone.3 The practical rule from long-range load development puts it plainly: shoot the ladder at the distance you intend to use the load.4 A charge picked at 100 yards and fired at 1,000 was never tested where it has to perform.
Loading the ladder, increments and rung count
Charge increments scale with case size. Common practice runs about 0.2 grains for a small case like the .223 Remington and 0.3 to 0.5 grains for larger ones, on the logic that each rung should move velocity enough to see without stepping clean over a window. Ten to fifteen rungs, starting at a safe published charge and climbing toward the top of the data, gives a ladder long enough to show structure. You stop climbing the moment pressure signs appear, meaning a flattened primer, a stiff bolt lift, or an ejector mark polished into the case head.
Weigh every charge to the kernel and freeze everything else. Same brass lot, same primer lot, same bullet lot, same seating depth, same trim length. A ladder is a one-variable test, and any extra variable you let in shows up as vertical that you will later credit to powder.
Number the rounds and keep them in order. A loading block with charge weights written on tape, loaded left to right and fired in that same order, is enough to keep the shot sequence on target mapped to the charge sequence in the block. Lose track of which rung is which and the target is unreadable.
Building the target and shooting the string
Build the target for vertical measurement rather than for group size. A tall sheet of paper with one small high-contrast aiming mark near the bottom, and a vertical scale running up from it, lets you read each impact's height directly. Putting the aim point low keeps the whole ladder on paper as the charges climb. Confirm a rough zero with foulers at the lowest charge first, so the string starts on the paper instead of above it.
Spot every shot as it lands. A spotting scope or a target camera lets you write down each point of impact against its rung number in real time, which is what saves the test when two rungs land in the same hole. Without live spotting you walk downrange to a sheet of anonymous holes and a guessing game about which charge made which.
Shoot deliberately and let the barrel breathe. Fire at a steady pace with real pauses, so heat is not climbing through the string while you work. A ladder shot fast from a hot barrel measures barrel temperature as much as it measures powder charge.
Reading vertical on the target
Read the height and ignore the width. The ladder's signal is elevation, so you measure how high each numbered impact sits above the aiming mark and plot that against charge weight. Horizontal scatter belongs to the wind and to you, not to the powder, and folding it into the read is the quickest route to a node that is not there.
The physics behind the read is simple enough. Faster shots hit higher and slower shots hit lower, and the wider the spread between the fastest and slowest rounds, the taller the group stands at long range.5 Impacts should therefore climb as charges climb, and the interesting part is where that climb pauses. Three or four consecutive rungs at one elevation mark a candidate charge window.
Run a chronograph under the string and you get a second plot for free. Velocity against charge weight sits beside elevation against charge weight, and the two should agree about where the flat run is. That pause is the same thing a velocity flat spot describes, and the traditional explanation is barrel harmonics: the barrel whips when the shot fires, the muzzle rises and falls in waves, and a charge that puts bullet exit at a repeatable point in that wave prints level with its neighbors.
Velocity spread is worth measuring for its own sake, node or no node. A low extreme spread, the gap between your fastest and slowest shot, and a low standard deviation point to stable internal ballistics and repeatable performance.6 Those numbers convert straight into vertical downrange, since with a 168 grain VLD an extreme spread of 30 feet per second works out to roughly 5 inches of vertical dispersion at 1,000 yards.7 That is 5 inches of scatter from velocity alone, before wind, position, or your own hold add anything to it.
Separating signal from wind and mirage
Wind is the ladder's main contaminant, and it does not limit itself to sideways. A crosswind pushes the bullet laterally, which you can see and discount, but it also moves impacts vertically through aerodynamic jump. The spinning bullet pitches into the side force, and the gyroscopic reaction to that pitch shows up as a vertical shift in impact.8 A switching wind writes vertical onto your target that looks exactly like a charge effect.
Shoot the ladder in calm air, then. The standard advice from long-range load development is to run the test in fairly calm conditions, with summer evenings a couple of hours before dark as the classic window.9 If the wind is strong enough to shove shots around the paper, the better move is to come back another day.
Read mirage as your wind gauge, because it shows you the air the bullet is actually flying through. Focus a spotting scope roughly halfway to the target and watch which way the heat waves lean, since wind from the left bends mirage to the right and stronger wind bends it further.10 Fire each rung in the same mirage picture you fired the last one in and you have taken most of the wind out of the comparison. That is ordinary wind reading work, and it counts for more on a ladder than on a group, because every rung is a sample of one.
What one ladder cannot tell you
A single ladder is a sample of one at every rung, and that is its structural limit. A tight cluster of three shots is little more than an accident in statistical terms, and one shot carries less information still.11 The flat run you found might be three charges genuinely doing the same thing, or three rounds of ordinary shot-to-shot noise that happened to land level.
The critique behind that has real weight. When researchers raised the sample sizes on node testing, the nodes they had been seeing disappeared.12 What shooters were reading as consistency in accuracy and velocity turned out, in those tests, to be random noise inside the normal limits of the system.13 A ladder cannot separate those two cases, because it does not carry the rounds to do it.
So treat the ladder as a screening tool rather than a verdict. Its real job is narrowing a wide charge range down to one candidate window in a single range trip, cheaply, and then handing that window to a test with enough rounds to confirm it. Shoot the ladder two or three times and overlay the results, letting the barrel drop back to ambient temperature between strings, and a window that repeats in all of them is worth believing.14 A window that shows once and never again was noise.
Round count is what settles the argument. The budget the sample-size critics suggest is that you should have load development finished, or that powder scrapped, within twenty or thirty shots.15 That works out to a ladder of twelve to fifteen rungs, then ten or so rounds at the best candidate charge to see whether the group and the velocity numbers hold. Burning 200 rounds of barrel life to chase a node is spending a real asset on a question the data cannot answer.
What I'd do
My approach is to run the ladder as a screening pass and nothing more. I'd load twelve to fifteen rungs in 0.3 grain steps for a mid-size case, shoot them at 600 yards over a chronograph on the calmest evening I can find, and read elevation only, looking for three or four rungs that sit level with each other.
Then I'd withhold trust until it repeats. I'd shoot the same ladder again on a different day, let the barrel cool between strings, and take a window seriously only when it shows up every time.14 After that I'd load ten rounds at the middle of the surviving window and shoot one ten-shot group at distance, with the chronograph running, and let those numbers make the call.
I'd hold the whole exercise to roughly thirty rounds before deciding to keep the powder or move on.15 Given the choice, I'd rather find a wide forgiving charge window and live in the middle of it than chase a narrow node that a chronograph cannot resolve and a barrel will move anyway as the throat erodes.
FAQ
What is a ladder test in reloading?
A ladder test is a load development method where you fire one round at each of a rising series of powder charges, all at the same aiming point, and read how high each shot lands. Charges that print at the same elevation mark a candidate accuracy window. It is also called the Audette ladder, after Creighton Audette, and it is built to be shot at long range rather than at 100 yards.
What distance should you shoot a ladder test at?
Shoot a ladder test at the distance you plan to use the load,4 and no closer than about 300 yards.2 Distance is what makes the test readable, because the vertical separation between neighboring charges grows with the square of the bullet's flight time. At 100 yards that flight time is too short for a small velocity difference to become measurable height on paper.
How many rounds does a ladder test take?
One ladder of twelve to fifteen rungs takes twelve to fifteen rounds plus foulers, but that is still a sample of one at every charge. A workable budget is roughly twenty to thirty rounds total to decide whether a powder stays or goes.15 Shooting the ladder two or three times and confirming with a ten-shot group at the surviving charge uses those rounds better than one very long ladder.
Can wind ruin a ladder test?
Wind can absolutely ruin a ladder test, and not only by pushing shots sideways. A crosswind also shifts impacts vertically through aerodynamic jump, the gyroscopic reaction that happens as the spinning bullet pitches into the side force.8 Because a ladder reads vertical and nothing else, that wind-driven vertical is indistinguishable from a charge effect, which is why the test should be shot in calm air.9
Citations
- (2012). Creighton Audette Ladder Testing. PrecisionRifleBlog.com.
- (2017). ILDM Load Testing (aka Ladder Test). Coyotestuff.com (Dave Affleck).
- (2017). ILDM Load Testing (aka Ladder Test). Coyotestuff.com (Dave Affleck).
- Long-Range Load Development (Ladder Test). 6mmBR.com (Jason Baney).
- (2021). Measuring Muzzle Velocity (Chapter 15, Modern Advancements in Long Range Shooting). Applied Ballistics, LLC (Bryan Litz).
- Brandon Lolkus. (2025). Ladder Testing vs. OCW: Understanding ES/SD in Load Development. Red Leg Guns.
- Long Range Hunting Forum. (2020). Velocity ES vs Vertical Dispersion at 1000 Yards. Long Range Hunting Forum.
- (2021). Vertical Deflection For Pellets In Crosswind. Hard Air Magazine.
- Long-Range Load Development (Ladder Test). 6mmBR.com (Jason Baney).
- John Antanies. (2016). How to Read Mirage to Estimate Wind Speed. American Hunter (NRA).
- Cal Zant. (2020). Precision & Group Size: Statistics for Shooters Part 3. PrecisionRifleBlog.com.
- Tyler Freel. (2024). Rifle Nodes: How You've Been Wasting Your Time and Money on Load Development. Outdoor Life.
- Tyler Freel. (2024). Rifle Nodes: How You've Been Wasting Your Time and Money on Load Development. Outdoor Life.
- Long-Range Load Development (Ladder Test). 6mmBR.com (Jason Baney).
- Tyler Freel. (2024). Rifle Nodes: How You've Been Wasting Your Time and Money on Load Development. Outdoor Life.