Load Specifications
Load data in caliber .257 Ackley Improved with .257 | 74gr | Reichenberg HDB Universal bullet and 34 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 60, Somchem S365 and Vihtavuori N150.
Important Notice: DO NOT go below Minimum Charge or above Maximum Charge. Since we have no control over the equipment and components used, any responsibility and liability for the results achieved is rejected.
Only powders/loads that match the current filter criteria are displayed: max pressure of a load ≤ 90% of max. standardized pressure, fill rate ≥ 80% and propellant combustion ≥ 95%. Use the sliders above the tables to adjust these thresholds.
Charge: Powder weight in grains. Start with the minimum load and work up carefully.
FR (Fill Rate): Case fill as a percentage. Values above 100% mean compressed loads.
MaxP / %: Maximum chamber pressure in bar and as a percentage of the standardized maximum for this caliber.
V(0): Muzzle velocity in feet per second (fps) at the standardized barrel length.
z (Powder Burn): Estimated propellant combustion percentage at bullet exit.
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Max Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 84% | 41,713 psi | 87% | 3238 fps | 100% |
| Accurate 4064 | <<locked>> | 86% | 42,105 psi | 87% | 3278 fps | 99.3% |
| ADI AR 2206H | <<locked>> | 82% | 43,033 psi | 89% | 3291 fps | 96% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 40,886 psi | 85% | 3251 fps | 96.4% |
| Bofors RP3 | <<locked>> | 88% | 43,468 psi | 90% | 3320 fps | 97.3% |
| Hodgdon H4895 | <<locked>> | 82% | 43,352 psi | 90% | 3307 fps | 96.7% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 42,496 psi | 88% | 3297 fps | 96.4% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 42,119 psi | 87% | 3323 fps | 96.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,592 psi | 72% | 2254 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 41,843 psi | 87% | 3251 fps | 96.2% |
| IMR 3031 | <<locked>> | 82% | 42,598 psi | 88% | 3327 fps | 99.9% |
| Lovex D073.6 | <<locked>> | 82% | 42,003 psi | 87% | 3271 fps | 98.6% |
| Lovex S060 | <<locked>> | 82% | 43,294 psi | 90% | 3228 fps | 96.2% |
| Lovex S062 | <<locked>> | 86% | 43,294 psi | 90% | 3281 fps | 97.5% |
| Norma 201 | <<locked>> | 82% | 42,235 psi | 88% | 3245 fps | 97.2% |
| Norma 202 | <<locked>> | 82% | 42,322 psi | 88% | 3264 fps | 99.1% |
| Norma 203B | <<locked>> | 86% | 43,569 psi | 90% | 3323 fps | 96.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,041 psi | 73% | 2306 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 43,598 psi | 90% | 3425 fps | 98.9% |
| Rottweil R 902 | <<locked>> | 84% | 42,685 psi | 89% | 3245 fps | 97.3% |
| Rottweil R 903 | <<locked>> | 90% | 43,613 psi | 90% | 3314 fps | 97% |
| Shooters World Match Rifle | <<locked>> | 82% | 42,003 psi | 87% | 3271 fps | 98.6% |
| Shooters World Precision | <<locked>> | 86% | 43,294 psi | 90% | 3281 fps | 97.5% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 41,104 psi | 85% | 3156 fps | 99.5% |
| Somchem S335 | <<locked>> | 82% | 43,323 psi | 90% | 3215 fps | 99.7% |
| Somchem S341 | <<locked>> | 82% | 43,366 psi | 90% | 3271 fps | 96% |
| Somchem S355 | <<locked>> | 88% | 41,553 psi | 86% | 3255 fps | 96.2% |
| Somchem S365 | <<locked>> | 98% | 41,901 psi | 87% | 3356 fps | 97.8% |
| Vihtavuori N135 | <<locked>> | 84% | 41,800 psi | 87% | 3245 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 42,786 psi | 89% | 3245 fps | 99.4% |
| Vihtavuori N150 | <<locked>> | 90% | 42,627 psi | 88% | 3245 fps | 97.9% |
| Vihtavuori N540 | <<locked>> | 84% | 41,524 psi | 86% | 3225 fps | 98.9% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 41,176 psi | 85% | 3209 fps | 96.2% |
| Winchester StaBALL Match | <<locked>> | 82% | 41,075 psi | 85% | 3248 fps | 96.1% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 80% | 36,332 psi | 75% | 3114 fps | 99.7% |
| Accurate 4064 | <<locked>> | 80% | 34,330 psi | 71% | 3077 fps | 97.6% |
| ADI AR 2206H | <<locked>> | 80% | 40,480 psi | 84% | 3225 fps | 95.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 38,377 psi | 80% | 3186 fps | 95.6% |
| Bofors RP3 | <<locked>> | 84% | 37,985 psi | 79% | 3186 fps | 95.6% |
| Hodgdon H4895 | <<locked>> | 80% | 40,770 psi | 85% | 3241 fps | 95.9% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 39,842 psi | 83% | 3235 fps | 95.5% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 36,738 psi | 76% | 3179 fps | 95% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,585 psi | 53% | 2021 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 39,044 psi | 81% | 3182 fps | 95.3% |
| IMR 3031 | <<locked>> | 80% | 39,610 psi | 82% | 3258 fps | 99.7% |
| Lovex D073.6 | <<locked>> | 80% | 39,146 psi | 81% | 3202 fps | 97.9% |
| Lovex S060 | <<locked>> | 80% | 40,770 psi | 85% | 3166 fps | 95.4% |
| Lovex S062 | <<locked>> | 80% | 35,708 psi | 74% | 3087 fps | 95.1% |
| Norma 201 | <<locked>> | 80% | 39,436 psi | 82% | 3176 fps | 96.4% |
| Norma 202 | <<locked>> | 80% | 39,711 psi | 82% | 3202 fps | 98.6% |
| Norma 203B | <<locked>> | 84% | 40,669 psi | 84% | 3251 fps | 95.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,846 psi | 54% | 2070 fps | 100% |
| ReloadSwiss RS 60 | 45.8 gr | 82% | 33,301 psi | 69% | 3123 fps | 95.1% |
| Rottweil R 902 | <<locked>> | 80% | 37,492 psi | 78% | 3114 fps | 95.7% |
| Rottweil R 903 | <<locked>> | 86% | 38,116 psi | 79% | 3179 fps | 95.2% |
| Shooters World Match Rifle | <<locked>> | 80% | 39,146 psi | 81% | 3202 fps | 97.9% |
| Shooters World Precision | <<locked>> | 80% | 35,708 psi | 74% | 3087 fps | 95.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 33,924 psi | 70% | 2979 fps | 98.1% |
| Somchem S335 | <<locked>> | 80% | 40,509 psi | 84% | 3150 fps | 99.3% |
| Somchem S341 | <<locked>> | 80% | 40,263 psi | 84% | 3196 fps | 95% |
| Somchem S355 | <<locked>> | 86% | 39,044 psi | 81% | 3189 fps | 95.3% |
| Somchem S365 | 49.7 gr | 94% | 36,492 psi | 76% | 3212 fps | 95.9% |
| Vihtavuori N135 | <<locked>> | 80% | 36,651 psi | 76% | 3123 fps | 99.7% |
| Vihtavuori N140 | <<locked>> | 80% | 37,478 psi | 78% | 3117 fps | 98.5% |
| Vihtavuori N150 | 44.2 gr | 84% | 34,795 psi | 72% | 3051 fps | 95.5% |
| Vihtavuori N540 | <<locked>> | 80% | 36,260 psi | 75% | 3094 fps | 97.7% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 38,363 psi | 80% | 3136 fps | 95.1% |
| Winchester StaBALL Match | <<locked>> | 80% | 38,348 psi | 80% | 3179 fps | 95.2% |
Recommended = one of the top powders for this cartridge and bullet combination.
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 34 powders for .257 Ackley Improved loaded with the .257 | 74gr | Reichenberg HDB Universal. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,425 fps; across all powders the maximum-charge window runs from 2,254 fps to 3,425 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 34 of the 34 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (332 MPa), the top charges use 72–90 %, leaving at least 10 % headroom. The 74.0 gr projectile in 0.257" calls for a 1:13.0 twist; slower twists will usually not stabilise this weight. Hodgdon TrailBoss, ReloadSwiss RS 14 reach 100 % fill or more at maximum charge, so these are compressed loads: they need a long drop tube to seat cleanly and react sensitively to the case capacity of your own brass lot. ReloadSwiss RS 60, Somchem S365, Vihtavuori N150 rank at the top here: for .257 Ackley Improved with the .257 | 74gr | Reichenberg HDB Universal they combine a high case fill with complete burn and sit in the upper velocity band. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.