History
Dan Dobbins and Al Ashton built the 6 Dasher around 2000, and the name is theirs welded together. Fire-form a 6mm BR Norma case to a sharp 40 degree shoulder and a straighter body and you blow out a few grains of extra powder capacity. What came out of that is one of the most accurate cartridges ever fired in 600 to 1,000 yard benchrest and F-class: tiny groups, mild recoil, long barrel life.
C.I.P. standardized the 6 Dasher in 2023, ending its long wildcat run; before that the dimensions came from the widely published case print rather than an official datasheet. It stays a handloader's cartridge at heart: you fire-form your brass from 6mm BR and load it yourself, though Norma now produces dedicated Dasher brass and boutique makers such as Eagle Eye load it off the shelf.
Lineage
Take the 6mm BR Norma, fire-form it to the Ackley-style profile, and you get the Dasher: a .473 inch (.308-family) head, a small rifle primer, a 40 degree shoulder, and a short, fat body throwing .243 inch (6.17mm) bullets. It runs in a short action. The parent is the 6mm BR Norma. Its peers are the other efficient 6mm target rounds: the 6 BR, 6 BRA, 6XC, and the magazine-friendly 6 GT, drawn up to solve the Dasher's feeding troubles.
Specifications
| Spec | Value |
|---|---|
| Case type | Rimless, bottlenecked (40° shoulder, fire-formed) |
| Bullet diameter | 6.17 mm (.243 in) |
| Neck diameter | 6.86 mm (.270 in) |
| Shoulder diameter | 11.66 mm (.459 in) |
| Base diameter | 11.99 mm (.472 in) |
| Rim diameter | 12.01 mm (.473 in) |
| Case length | 39.37 mm (1.550 in) |
| Overall length | 57.15 mm (2.250 in) |
| Case capacity | ~40 gr H2O (nominal) |
| Primer size | Small rifle |
| Belted | No |
| Rifling twist | 1 in 7.5 in (recommended, for heavy 6mm match) |
| Max pressure | 4,400 bar (~63,800 psi), C.I.P. |
| Recommended barrel | 26 in, 1:7.5 twist |
Barrel Design
The Dasher feeds on heavy 105 to 110 grain 6mm match bullets, so the twist I'd recommend is 1:7.5, fast enough for the longest of them with margin and standard practice on a barrel built for distance. A 1:8 handles the common 105 to 109 grain loads; the faster twist just protects the heaviest.
It is an efficient case, not an overbore one, and that efficiency is what gives the mild recoil and the long barrel life. The baseline I'd recommend sits at 26 inches, which collects the velocity the case has to give; a longer tube chases almost nothing, and a sensible one gives you accuracy life. The Dasher does not burn throats. The tables below are computed at that 26 inch barrel, and since there is no mass-market factory 6 Dasher load, confirm your own velocity on a chronograph before you trust any dial.
Match Ammo Performance
LOAD-X · 108 gr ELD Match $3.85/rd
| Range (yd) | Velocity (fps) | Elevation (mil) | Energy (ft-lb) | Windage (mil) |
|---|---|---|---|---|
| 0 | 2950 | -0.4 | 2087 | 0.3 |
| 100 | 2785 | 0.0 | 1859 | 0.2 |
| 200 | 2624 | -0.4 | 1651 | 0.3 |
| 300 | 2468 | -1.0 | 1461 | 0.5 |
| 400 | 2318 | -1.7 | 1289 | 0.7 |
| 500 | 2174 | -2.5 | 1133 | 0.9 |
| 600 | 2035 | -3.4 | 993 | 1.1 |
| 700 | 1900 | -4.3 | 866 | 1.4 |
| 800 | 1770 | -5.4 | 751 | 1.6 |
| 900 | 1644 | -6.6 | 648 | 1.9 |
| 1000 | 1522 | -7.9 | 555 | 2.2 |
| 1100 | 1404 | -9.3 | 473 | 2.5 |
| 1200 | 1291 | -11.0 | 400 | 2.9 |
| 1300 | 1184 | -12.8 | 336 | 3.3 |
| 1400 | 1098 | -14.9 | 289 | 3.7 |
| 1500 | 1053 | -17.2 | 266 | 4.1 |
Muzzle velocity 2950 fps is the factory figure from a 26 in test barrel. Expect your own barrel to read a little differently. Velocity is color coded green supersonic, yellow transonic, red subsonic; treat transonic and subsonic rows as approximate.
Trajectory
FAQ
What barrel length and twist should I run?
A 1:7.5 twist for the heavy 105 to 110 grain 6mm match bullets, and a 26 inch barrel to collect the velocity. The Dasher is efficient rather than overbore, so a longer barrel adds little, and barrel life is one of the cartridge's main attractions.
Is the 6 Dasher a SAAMI cartridge?
Not SAAMI, but it is C.I.P.-standardized: C.I.P. listed the 6 Dasher in 2023 (Norma submitted it), ending its long wildcat run. It began as a 6mm BR wildcat you fire-form and handload, and Norma now makes dedicated Dasher brass and loaded ammunition. The dimensions on this page match that C.I.P. standard.
How does it compare to the 6mm BR and 6 GT?
The Dasher adds a few grains of capacity and a little velocity over its 6mm BR parent while keeping the BR's legendary accuracy. Against the 6 GT, it gives up nothing in accuracy but feeds poorly from box magazines, the one weakness the 6 GT was drawn up to fix for practical competition.
What is it good for?
Precision work where accuracy is everything: 600 to 1,000 yard benchrest, F-class, and single-feed or carefully fed precision rifle shooting. Its mild recoil and long barrel life make it a load-development favorite. The magazine-fed 6 GT is the better pick for fast-paced PRS stages.