Load Specifications
Bullet Manufacturer:Sierra
Bullet Weight:70 gr
Bullet Diameter:0.257"
Bullet Length:<<locked>>
Caliber:.257 Ackley Improved load data
Case Length (l3):2.333"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:63 Grains of Water
Primer Size:Large Rifle (LR)
Barrel Length:24"
Max. allowed Pressure:48,200 psi
Recommended Twist Rate:1:11.5
Load data in caliber .257 Ackley Improved with .257 | 70gr | Sierra Tipped VarmintKing bullet and 126 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 60, Accurate 4064 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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 86% | 42,192 psi | 88% | 3323 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 42,946 psi | 89% | 3340 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 42,192 psi | 88% | 3323 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 43,439 psi | 90% | 3353 fps | 100% |
| Accurate 4064 | <<locked>> | 88% | 42,569 psi | 88% | 3360 fps | 99.1% |
| Accurate 4064 | <<locked>> | 88% | 42,975 psi | 89% | 3369 fps | 99.2% |
| Accurate 4064 | <<locked>> | 88% | 42,569 psi | 88% | 3360 fps | 99.1% |
| Accurate 4064 | <<locked>> | 88% | 43,424 psi | 90% | 3383 fps | 99.3% |
| ADI Benchmark 8208 | <<locked>> | 82% | 43,265 psi | 90% | 3340 fps | 96.8% |
| ADI Benchmark 8208 | <<locked>> | 82% | 43,598 psi | 90% | 3350 fps | 96.9% |
| ADI Benchmark 8208 | <<locked>> | 82% | 43,265 psi | 90% | 3340 fps | 96.8% |
| Alliant AR-Comp | <<locked>> | 82% | 42,293 psi | 88% | 3366 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 42,815 psi | 89% | 3376 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 42,293 psi | 88% | 3366 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 43,337 psi | 90% | 3389 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 41,481 psi | 86% | 3333 fps | 95.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 42,076 psi | 87% | 3350 fps | 96.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 41,481 psi | 86% | 3333 fps | 95.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 42,511 psi | 88% | 3363 fps | 96.4% |
| Bofors RP3 | <<locked>> | 88% | 41,321 psi | 86% | 3337 fps | 96% |
| Bofors RP3 | <<locked>> | 88% | 41,655 psi | 86% | 3343 fps | 96.2% |
| Bofors RP3 | <<locked>> | 88% | 41,321 psi | 86% | 3337 fps | 96% |
| Bofors RP3 | <<locked>> | 88% | 42,351 psi | 88% | 3363 fps | 96.4% |
| Hodgdon BL-C2 | <<locked>> | 82% | 41,727 psi | 87% | 3343 fps | 97% |
| Hodgdon BL-C2 | <<locked>> | 82% | 42,351 psi | 88% | 3360 fps | 97.3% |
| Hodgdon BL-C2 | <<locked>> | 82% | 41,727 psi | 87% | 3343 fps | 97% |
| Hodgdon BL-C2 | <<locked>> | 82% | 42,728 psi | 89% | 3373 fps | 97.4% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 42,728 psi | 89% | 3406 fps | 96.4% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 43,337 psi | 90% | 3422 fps | 96.7% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 42,728 psi | 89% | 3406 fps | 96.4% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,374 psi | 71% | 2306 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,490 psi | 72% | 2313 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,374 psi | 71% | 2306 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,403 psi | 71% | 2313 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 42,931 psi | 89% | 3346 fps | 95.9% |
| Hodgdon VARGET | <<locked>> | 84% | 43,337 psi | 90% | 3356 fps | 96.1% |
| IMR 3031 | <<locked>> | 84% | 43,221 psi | 90% | 3419 fps | 99.8% |
| IMR 3031 | <<locked>> | 82% | 40,857 psi | 85% | 3363 fps | 99.6% |
| IMR 3031 | <<locked>> | 84% | 43,221 psi | 90% | 3419 fps | 99.8% |
| IMR 3031 | <<locked>> | 82% | 41,104 psi | 85% | 3369 fps | 99.6% |
| IMR 8208 XBR | <<locked>> | 82% | 43,265 psi | 90% | 3340 fps | 96.8% |
| IMR 8208 XBR | <<locked>> | 82% | 43,598 psi | 90% | 3350 fps | 96.9% |
| IMR 8208 XBR | <<locked>> | 82% | 43,265 psi | 90% | 3340 fps | 96.8% |
| Lovex D073.6 | <<locked>> | 84% | 42,583 psi | 88% | 3353 fps | 98.2% |
| Lovex D073.6 | <<locked>> | 84% | 43,221 psi | 90% | 3369 fps | 98.4% |
| Lovex D073.6 | <<locked>> | 84% | 42,583 psi | 88% | 3353 fps | 98.2% |
| Lovex D073.6 | <<locked>> | 82% | 40,727 psi | 84% | 3314 fps | 97.9% |
| Lovex S062 | <<locked>> | 86% | 41,350 psi | 86% | 3301 fps | 96.4% |
| Lovex S062 | <<locked>> | 86% | 41,713 psi | 87% | 3310 fps | 96.5% |
| Lovex S062 | <<locked>> | 86% | 41,350 psi | 86% | 3301 fps | 96.4% |
| Lovex S062 | <<locked>> | 86% | 42,148 psi | 87% | 3323 fps | 96.7% |
| Norma 201 | <<locked>> | 84% | 42,975 psi | 89% | 3330 fps | 96.8% |
| Norma 201 | <<locked>> | 84% | 43,352 psi | 90% | 3343 fps | 97% |
| Norma 201 | <<locked>> | 84% | 42,975 psi | 89% | 3330 fps | 96.8% |
| Norma 201 | <<locked>> | 82% | 41,176 psi | 85% | 3291 fps | 96.4% |
| Norma 202 | <<locked>> | 84% | 43,018 psi | 89% | 3350 fps | 98.9% |
| Norma 202 | <<locked>> | 82% | 40,741 psi | 85% | 3297 fps | 98.5% |
| Norma 202 | <<locked>> | 84% | 43,018 psi | 89% | 3350 fps | 98.9% |
| Norma 202 | <<locked>> | 82% | 41,205 psi | 85% | 3310 fps | 98.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,534 psi | 72% | 2356 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,650 psi | 72% | 2362 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,534 psi | 72% | 2356 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,795 psi | 72% | 2369 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 41,423 psi | 86% | 3428 fps | 97.8% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 41,901 psi | 87% | 3445 fps | 98% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 41,423 psi | 86% | 3428 fps | 97.8% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 42,496 psi | 88% | 3461 fps | 98.2% |
| Rottweil R 902 | <<locked>> | 86% | 43,468 psi | 90% | 3330 fps | 96.9% |
| Rottweil R 902 | <<locked>> | 84% | 41,191 psi | 85% | 3278 fps | 96.3% |
| Rottweil R 902 | <<locked>> | 86% | 43,468 psi | 90% | 3330 fps | 96.9% |
| Rottweil R 902 | <<locked>> | 84% | 41,655 psi | 86% | 3291 fps | 96.5% |
| Rottweil R 903 | <<locked>> | 90% | 42,235 psi | 88% | 3350 fps | 96.1% |
| Shooters World Match Rifle | <<locked>> | 84% | 42,583 psi | 88% | 3353 fps | 98.2% |
| Shooters World Match Rifle | <<locked>> | 84% | 43,221 psi | 90% | 3369 fps | 98.4% |
| Shooters World Match Rifle | <<locked>> | 84% | 42,583 psi | 88% | 3353 fps | 98.2% |
| Shooters World Match Rifle | <<locked>> | 82% | 40,727 psi | 84% | 3314 fps | 97.9% |
| Shooters World Precision | <<locked>> | 86% | 41,350 psi | 86% | 3301 fps | 96.4% |
| Shooters World Precision | <<locked>> | 86% | 41,713 psi | 87% | 3310 fps | 96.5% |
| Shooters World Precision | <<locked>> | 86% | 41,350 psi | 86% | 3301 fps | 96.4% |
| Shooters World Precision | <<locked>> | 86% | 42,148 psi | 87% | 3323 fps | 96.7% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 41,742 psi | 87% | 3241 fps | 98.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 42,380 psi | 88% | 3258 fps | 98.7% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 41,742 psi | 87% | 3241 fps | 98.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 42,612 psi | 88% | 3264 fps | 98.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 41,655 psi | 86% | 3238 fps | 99.3% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 42,264 psi | 88% | 3251 fps | 99.4% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 41,655 psi | 86% | 3238 fps | 99.3% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 42,670 psi | 89% | 3261 fps | 99.5% |
| Somchem S335 | <<locked>> | 82% | 41,524 psi | 86% | 3241 fps | 99.1% |
| Somchem S335 | <<locked>> | 82% | 41,916 psi | 87% | 3251 fps | 99.2% |
| Somchem S335 | <<locked>> | 82% | 41,524 psi | 86% | 3241 fps | 99.1% |
| Somchem S335 | <<locked>> | 82% | 42,293 psi | 88% | 3264 fps | 99.3% |
| Somchem S355 | <<locked>> | 90% | 42,830 psi | 89% | 3353 fps | 95.9% |
| Somchem S355 | <<locked>> | 90% | 43,192 psi | 90% | 3366 fps | 96.1% |
| Somchem S365ᴾ | <<locked>> | 100% | 42,250 psi | 88% | 3428 fps | 97.3% |
| Somchem S365ᴾ | <<locked>> | 100% | 42,743 psi | 89% | 3445 fps | 97.5% |
| Somchem S365ᴾ | <<locked>> | 100% | 42,250 psi | 88% | 3428 fps | 97.3% |
| Somchem S365ᴾ | <<locked>> | 100% | 43,294 psi | 90% | 3458 fps | 97.7% |
| Vihtavuori N133 | <<locked>> | 82% | 41,843 psi | 87% | 3245 fps | 99.9% |
| Vihtavuori N133 | <<locked>> | 82% | 42,482 psi | 88% | 3264 fps | 99.9% |
| Vihtavuori N133 | <<locked>> | 82% | 41,843 psi | 87% | 3245 fps | 99.9% |
| Vihtavuori N133 | <<locked>> | 82% | 42,670 psi | 89% | 3268 fps | 99.9% |
| Vihtavuori N135 | <<locked>> | 86% | 42,177 psi | 88% | 3327 fps | 100% |
| Vihtavuori N135 | <<locked>> | 86% | 42,844 psi | 89% | 3343 fps | 100% |
| Vihtavuori N135 | <<locked>> | 86% | 42,177 psi | 88% | 3327 fps | 100% |
| Vihtavuori N135 | <<locked>> | 86% | 43,352 psi | 90% | 3356 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 43,511 psi | 90% | 3330 fps | 99.2% |
| Vihtavuori N140 | <<locked>> | 84% | 41,234 psi | 86% | 3278 fps | 98.9% |
| Vihtavuori N140 | <<locked>> | 86% | 43,511 psi | 90% | 3330 fps | 99.2% |
| Vihtavuori N140 | <<locked>> | 84% | 41,655 psi | 86% | 3291 fps | 99% |
| Vihtavuori N150 | <<locked>> | 92% | 43,337 psi | 90% | 3327 fps | 97.5% |
| Vihtavuori N150 | <<locked>> | 90% | 40,944 psi | 85% | 3274 fps | 96.9% |
| Vihtavuori N150 | <<locked>> | 92% | 43,337 psi | 90% | 3327 fps | 97.5% |
| Vihtavuori N150 | <<locked>> | 90% | 41,365 psi | 86% | 3287 fps | 97.1% |
| Vihtavuori N530 | <<locked>> | 82% | 43,410 psi | 90% | 3333 fps | 96.9% |
| Vihtavuori N530 | <<locked>> | 82% | 43,410 psi | 90% | 3333 fps | 96.9% |
| Vihtavuori N540 | <<locked>> | 86% | 42,163 psi | 87% | 3307 fps | 98.6% |
| Vihtavuori N540 | <<locked>> | 86% | 42,757 psi | 89% | 3320 fps | 98.8% |
| Vihtavuori N540 | <<locked>> | 86% | 42,163 psi | 87% | 3307 fps | 98.6% |
| Vihtavuori N540 | <<locked>> | 86% | 43,149 psi | 90% | 3333 fps | 98.9% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 42,902 psi | 89% | 3314 fps | 96.2% |
| Winchester 748 | <<locked>> | 82% | 42,380 psi | 88% | 3376 fps | 97.5% |
| Winchester 748 | <<locked>> | 82% | 43,033 psi | 89% | 3389 fps | 97.7% |
| Winchester 748 | <<locked>> | 82% | 42,380 psi | 88% | 3376 fps | 97.5% |
| Winchester 748 | <<locked>> | 82% | 43,468 psi | 90% | 3402 fps | 97.9% |
| Winchester StaBALL Match | <<locked>> | 84% | 42,670 psi | 89% | 3360 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% | 34,360 psi | 71% | 3130 fps | 99.1% |
| Accurate 2495 | <<locked>> | 80% | 34,795 psi | 72% | 3143 fps | 99.2% |
| Accurate 2495 | <<locked>> | 80% | 34,360 psi | 71% | 3130 fps | 99.1% |
| Accurate 2495 | <<locked>> | 80% | 35,244 psi | 73% | 3156 fps | 99.3% |
| Accurate 4064 | 42.1 gr | 80% | 32,445 psi | 67% | 3091 fps | 96.3% |
| Accurate 4064 | 42.1 gr | 80% | 32,851 psi | 68% | 3104 fps | 96.5% |
| Accurate 4064 | 42.1 gr | 80% | 32,445 psi | 67% | 3091 fps | 96.3% |
| Accurate 4064 | 42.1 gr | 80% | 33,286 psi | 69% | 3117 fps | 96.7% |
| ADI Benchmark 8208 | <<locked>> | 80% | 40,393 psi | 84% | 3271 fps | 95.9% |
| ADI Benchmark 8208 | <<locked>> | 80% | 41,031 psi | 85% | 3287 fps | 96.2% |
| ADI Benchmark 8208 | <<locked>> | 80% | 40,393 psi | 84% | 3271 fps | 95.9% |
| Alliant AR-Comp | <<locked>> | 80% | 39,494 psi | 82% | 3304 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 39,972 psi | 83% | 3317 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 39,494 psi | 82% | 3304 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 40,263 psi | 84% | 3323 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 38,914 psi | 81% | 3268 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 39,276 psi | 81% | 3281 fps | 95.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 38,914 psi | 81% | 3268 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 39,682 psi | 82% | 3291 fps | 95.5% |
| Bofors RP3 | <<locked>> | 86% | 38,464 psi | 80% | 3261 fps | 95% |
| Bofors RP3 | <<locked>> | 86% | 39,059 psi | 81% | 3281 fps | 95.3% |
| Bofors RP3 | <<locked>> | 86% | 38,464 psi | 80% | 3261 fps | 95% |
| Bofors RP3 | <<locked>> | 86% | 39,479 psi | 82% | 3291 fps | 95.5% |
| Hodgdon BL-C2 | <<locked>> | 80% | 38,914 psi | 81% | 3274 fps | 96.2% |
| Hodgdon BL-C2 | <<locked>> | 80% | 39,291 psi | 82% | 3284 fps | 96.4% |
| Hodgdon BL-C2 | <<locked>> | 80% | 38,914 psi | 81% | 3274 fps | 96.2% |
| Hodgdon BL-C2 | <<locked>> | 80% | 39,682 psi | 82% | 3294 fps | 96.5% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 39,885 psi | 83% | 3330 fps | 95.4% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 40,451 psi | 84% | 3350 fps | 95.7% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 39,885 psi | 83% | 3330 fps | 95.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,367 psi | 53% | 2067 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,541 psi | 53% | 2077 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,367 psi | 53% | 2067 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,527 psi | 53% | 2080 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 40,335 psi | 84% | 3281 fps | 95.1% |
| Hodgdon VARGET | <<locked>> | 82% | 40,756 psi | 85% | 3294 fps | 95.3% |
| IMR 3031 | <<locked>> | 80% | 37,492 psi | 78% | 3278 fps | 99% |
| IMR 3031 | <<locked>> | 80% | 37,927 psi | 79% | 3291 fps | 99.1% |
| IMR 3031 | <<locked>> | 80% | 37,492 psi | 78% | 3278 fps | 99% |
| IMR 3031 | <<locked>> | 80% | 38,450 psi | 80% | 3304 fps | 99.3% |
| IMR 8208 XBR | <<locked>> | 80% | 40,393 psi | 84% | 3271 fps | 95.9% |
| IMR 8208 XBR | <<locked>> | 80% | 41,031 psi | 85% | 3287 fps | 96.2% |
| IMR 8208 XBR | <<locked>> | 80% | 40,393 psi | 84% | 3271 fps | 95.9% |
| Lovex D073.6 | <<locked>> | 80% | 36,912 psi | 77% | 3212 fps | 96.7% |
| Lovex D073.6 | <<locked>> | 80% | 37,536 psi | 78% | 3232 fps | 97% |
| Lovex D073.6 | <<locked>> | 80% | 36,912 psi | 77% | 3212 fps | 96.7% |
| Lovex D073.6 | <<locked>> | 80% | 37,985 psi | 79% | 3241 fps | 97.1% |
| Lovex S062 | <<locked>> | 84% | 38,595 psi | 80% | 3232 fps | 95.5% |
| Lovex S062 | <<locked>> | 84% | 39,218 psi | 81% | 3248 fps | 95.7% |
| Lovex S062 | <<locked>> | 84% | 38,595 psi | 80% | 3232 fps | 95.5% |
| Lovex S062 | <<locked>> | 82% | 37,028 psi | 77% | 3189 fps | 95% |
| Norma 201 | <<locked>> | 80% | 37,681 psi | 78% | 3196 fps | 95.1% |
| Norma 201 | <<locked>> | 80% | 38,029 psi | 79% | 3205 fps | 95.3% |
| Norma 201 | <<locked>> | 80% | 37,681 psi | 78% | 3196 fps | 95.1% |
| Norma 201 | <<locked>> | 80% | 38,450 psi | 80% | 3219 fps | 95.5% |
| Norma 202 | <<locked>> | 80% | 37,884 psi | 79% | 3222 fps | 97.7% |
| Norma 202 | <<locked>> | 80% | 38,276 psi | 79% | 3232 fps | 97.8% |
| Norma 202 | <<locked>> | 80% | 37,884 psi | 79% | 3222 fps | 97.7% |
| Norma 202 | <<locked>> | 80% | 38,450 psi | 80% | 3241 fps | 97.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,585 psi | 53% | 2116 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,773 psi | 53% | 2126 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,585 psi | 53% | 2116 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,744 psi | 53% | 2126 fps | 100% |
| ReloadSwiss RS 60 | 48.5 gr | 86% | 36,158 psi | 75% | 3274 fps | 95.7% |
| ReloadSwiss RS 60 | 48.5 gr | 86% | 36,651 psi | 76% | 3294 fps | 96% |
| ReloadSwiss RS 60 | 48.5 gr | 86% | 36,158 psi | 75% | 3274 fps | 95.7% |
| ReloadSwiss RS 60 | 47.4 gr | 84% | 34,577 psi | 72% | 3225 fps | 95% |
| Rottweil R 902 | <<locked>> | 82% | 38,101 psi | 79% | 3196 fps | 95.2% |
| Rottweil R 902 | <<locked>> | 82% | 38,711 psi | 80% | 3215 fps | 95.5% |
| Rottweil R 902 | <<locked>> | 82% | 38,101 psi | 79% | 3196 fps | 95.2% |
| Rottweil R 902 | <<locked>> | 82% | 38,914 psi | 81% | 3222 fps | 95.7% |
| Rottweil R 903 | <<locked>> | 88% | 39,363 psi | 82% | 3281 fps | 95.1% |
| Shooters World Match Rifle | <<locked>> | 80% | 36,912 psi | 77% | 3212 fps | 96.7% |
| Shooters World Match Rifle | <<locked>> | 80% | 37,536 psi | 78% | 3232 fps | 97% |
| Shooters World Match Rifle | <<locked>> | 80% | 36,912 psi | 77% | 3212 fps | 96.7% |
| Shooters World Match Rifle | <<locked>> | 80% | 37,985 psi | 79% | 3241 fps | 97.1% |
| Shooters World Precision | <<locked>> | 84% | 38,595 psi | 80% | 3232 fps | 95.5% |
| Shooters World Precision | <<locked>> | 84% | 39,218 psi | 81% | 3248 fps | 95.7% |
| Shooters World Precision | <<locked>> | 84% | 38,595 psi | 80% | 3232 fps | 95.5% |
| Shooters World Precision | <<locked>> | 82% | 37,028 psi | 77% | 3189 fps | 95% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 39,175 psi | 81% | 3176 fps | 98% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 39,566 psi | 82% | 3189 fps | 98.2% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 39,175 psi | 81% | 3176 fps | 98% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 39,987 psi | 83% | 3202 fps | 98.3% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 32,140 psi | 67% | 2989 fps | 97% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 32,503 psi | 67% | 3002 fps | 97.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 32,140 psi | 67% | 2989 fps | 97% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 32,880 psi | 68% | 3015 fps | 97.4% |
| Somchem S335 | <<locked>> | 80% | 38,827 psi | 81% | 3179 fps | 98.6% |
| Somchem S335 | <<locked>> | 80% | 39,175 psi | 81% | 3189 fps | 98.8% |
| Somchem S335 | <<locked>> | 80% | 38,827 psi | 81% | 3179 fps | 98.6% |
| Somchem S335 | <<locked>> | 80% | 39,610 psi | 82% | 3202 fps | 98.9% |
| Somchem S355 | <<locked>> | 88% | 39,943 psi | 83% | 3281 fps | 95% |
| Somchem S355 | <<locked>> | 88% | 40,393 psi | 84% | 3297 fps | 95.2% |
| Somchem S365 | <<locked>> | 96% | 36,941 psi | 77% | 3284 fps | 95.2% |
| Somchem S365 | <<locked>> | 96% | 37,420 psi | 78% | 3301 fps | 95.6% |
| Somchem S365 | <<locked>> | 96% | 36,941 psi | 77% | 3284 fps | 95.2% |
| Somchem S365 | <<locked>> | 96% | 38,000 psi | 79% | 3317 fps | 95.9% |
| Vihtavuori N133 | <<locked>> | 80% | 39,247 psi | 81% | 3186 fps | 99.6% |
| Vihtavuori N133 | <<locked>> | 80% | 39,653 psi | 82% | 3199 fps | 99.7% |
| Vihtavuori N133 | <<locked>> | 80% | 39,247 psi | 81% | 3186 fps | 99.6% |
| Vihtavuori N133 | <<locked>> | 80% | 40,074 psi | 83% | 3212 fps | 99.8% |
| Vihtavuori N135 | <<locked>> | 80% | 34,505 psi | 72% | 3136 fps | 99.1% |
| Vihtavuori N135 | <<locked>> | 80% | 34,940 psi | 72% | 3150 fps | 99.2% |
| Vihtavuori N135 | <<locked>> | 80% | 34,505 psi | 72% | 3136 fps | 99.1% |
| Vihtavuori N135 | <<locked>> | 80% | 35,418 psi | 73% | 3166 fps | 99.3% |
| Vihtavuori N140 | <<locked>> | 80% | 35,723 psi | 74% | 3140 fps | 97.5% |
| Vihtavuori N140 | <<locked>> | 80% | 36,100 psi | 75% | 3150 fps | 97.6% |
| Vihtavuori N140 | <<locked>> | 80% | 35,723 psi | 74% | 3140 fps | 97.5% |
| Vihtavuori N140 | <<locked>> | 80% | 36,521 psi | 76% | 3163 fps | 97.8% |
| Vihtavuori N150 | 46.8 gr | 88% | 37,884 psi | 79% | 3196 fps | 95.9% |
| Vihtavuori N150 | 45.8 gr | 86% | 35,853 psi | 74% | 3143 fps | 95.2% |
| Vihtavuori N150 | 46.8 gr | 88% | 37,884 psi | 79% | 3196 fps | 95.9% |
| Vihtavuori N150 | 45.8 gr | 86% | 36,216 psi | 75% | 3156 fps | 95.4% |
| Vihtavuori N530 | <<locked>> | 80% | 40,466 psi | 84% | 3264 fps | 96.1% |
| Vihtavuori N530 | <<locked>> | 80% | 40,466 psi | 84% | 3264 fps | 96.1% |
| Vihtavuori N540 | <<locked>> | 80% | 34,592 psi | 72% | 3114 fps | 96.5% |
| Vihtavuori N540 | <<locked>> | 80% | 34,911 psi | 72% | 3120 fps | 96.7% |
| Vihtavuori N540 | <<locked>> | 80% | 34,592 psi | 72% | 3114 fps | 96.5% |
| Vihtavuori N540 | <<locked>> | 80% | 35,273 psi | 73% | 3133 fps | 96.9% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 40,176 psi | 83% | 3245 fps | 95.2% |
| Winchester 748 | <<locked>> | 80% | 39,479 psi | 82% | 3304 fps | 96.7% |
| Winchester 748 | <<locked>> | 80% | 40,118 psi | 83% | 3320 fps | 96.9% |
| Winchester 748 | <<locked>> | 80% | 39,479 psi | 82% | 3304 fps | 96.7% |
| Winchester 748 | <<locked>> | 80% | 40,553 psi | 84% | 3330 fps | 97.1% |
| Winchester StaBALL Match | <<locked>> | 82% | 39,871 psi | 83% | 3287 fps | 95.1% |
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 126 powders for .257 Ackley Improved loaded with the .257 | 70gr | Sierra Tipped VarmintKing. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,461 fps; across all powders the maximum-charge window runs from 2,306 fps to 3,461 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 126 of the 126 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (332 MPa), the top charges use 71–90 %, leaving at least 10 % headroom. The 70.0 gr projectile in 0.257" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. Hodgdon TrailBoss, Hodgdon TrailBoss, Hodgdon TrailBoss 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, Accurate 4064, Vihtavuori N150 rank at the top here: for .257 Ackley Improved with the .257 | 70gr | Sierra Tipped VarmintKing 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.