Load Specifications
Load data in caliber .257 Ackley Improved with .257 | 58gr | Peregrine VRG-2 bullet and 40 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Accurate 4064, Vihtavuori N135 and Accurate 2495.
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 2015 | <<locked>> | 82% | 40,944 psi | 85% | 3510 fps | 99.2% |
| Accurate 2015 | <<locked>> | 84% | 42,786 psi | 89% | 3560 fps | 99.4% |
| Accurate 2495 | <<locked>> | 88% | 40,814 psi | 85% | 3543 fps | 99.4% |
| Accurate 2495 | <<locked>> | 90% | 42,308 psi | 88% | 3583 fps | 99.6% |
| Accurate 2520 | <<locked>> | 84% | 43,149 psi | 90% | 3602 fps | 97.1% |
| Accurate 2520 | <<locked>> | 84% | 42,018 psi | 87% | 3579 fps | 96.8% |
| Accurate 4064 | <<locked>> | 90% | 41,060 psi | 85% | 3570 fps | 97.6% |
| Accurate 4064 | <<locked>> | 92% | 42,540 psi | 88% | 3612 fps | 98% |
| Alliant AR-Comp | <<locked>> | 84% | 41,147 psi | 85% | 3609 fps | 100% |
| Alliant AR-Comp | <<locked>> | 86% | 42,960 psi | 89% | 3655 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 33,547 psi | 70% | 2516 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 33,315 psi | 69% | 2516 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 41,989 psi | 87% | 3648 fps | 98.9% |
| IMR 3031 | <<locked>> | 86% | 41,002 psi | 85% | 3629 fps | 98.7% |
| Lovex D073.6 | <<locked>> | 86% | 41,481 psi | 86% | 3570 fps | 96.6% |
| Lovex D073.6 | <<locked>> | 86% | 40,393 psi | 84% | 3547 fps | 96.2% |
| Norma 202 | <<locked>> | 86% | 42,279 psi | 88% | 3579 fps | 97.5% |
| Norma 202 | <<locked>> | 86% | 41,263 psi | 86% | 3560 fps | 97.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 33,794 psi | 70% | 2575 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 33,475 psi | 69% | 2572 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 43,134 psi | 89% | 3701 fps | 96.6% |
| Rottweil R 901 | <<locked>> | 84% | 43,265 psi | 90% | 3583 fps | 97.4% |
| Rottweil R 901 | <<locked>> | 84% | 42,061 psi | 87% | 3556 fps | 97.1% |
| Shooters World Match Rifle | <<locked>> | 86% | 41,481 psi | 86% | 3570 fps | 96.6% |
| Shooters World Match Rifle | <<locked>> | 86% | 40,393 psi | 84% | 3547 fps | 96.2% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 41,423 psi | 86% | 3478 fps | 97.2% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 43,207 psi | 90% | 3527 fps | 97.7% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 41,133 psi | 85% | 3468 fps | 98.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 42,902 psi | 89% | 3510 fps | 98.6% |
| Somchem S335 | <<locked>> | 86% | 43,613 psi | 90% | 3537 fps | 98.5% |
| Somchem S335 | <<locked>> | 86% | 42,641 psi | 88% | 3520 fps | 98.4% |
| Vihtavuori N130 | <<locked>> | 82% | 43,018 psi | 89% | 3530 fps | 99.8% |
| Vihtavuori N133 | <<locked>> | 84% | 41,350 psi | 86% | 3488 fps | 99.2% |
| Vihtavuori N133 | <<locked>> | 86% | 43,149 psi | 90% | 3537 fps | 99.5% |
| Vihtavuori N135 | <<locked>> | 88% | 41,234 psi | 86% | 3563 fps | 99.4% |
| Vihtavuori N135 | <<locked>> | 90% | 42,960 psi | 89% | 3606 fps | 99.6% |
| Vihtavuori N140 | <<locked>> | 88% | 42,873 psi | 89% | 3560 fps | 98% |
| Vihtavuori N140 | <<locked>> | 88% | 41,959 psi | 87% | 3543 fps | 97.8% |
| Vihtavuori N540 | <<locked>> | 88% | 41,640 psi | 86% | 3533 fps | 97.3% |
| Vihtavuori N540 | <<locked>> | 90% | 43,526 psi | 90% | 3583 fps | 97.7% |
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 2015 | <<locked>> | 80% | 38,189 psi | 79% | 3438 fps | 98.6% |
| Accurate 2015 | <<locked>> | 80% | 37,159 psi | 77% | 3419 fps | 98.4% |
| Accurate 2495 | 43.3 gr | 80% | 30,806 psi | 64% | 3258 fps | 96.6% |
| Accurate 2495 | 43.3 gr | 80% | 29,443 psi | 61% | 3215 fps | 96% |
| Accurate 2520 | <<locked>> | 80% | 37,318 psi | 77% | 3451 fps | 95.2% |
| Accurate 2520 | <<locked>> | 82% | 38,914 psi | 81% | 3501 fps | 95.8% |
| Accurate 4064 | 46.6 gr | 86% | 35,940 psi | 75% | 3428 fps | 95.9% |
| Accurate 4064 | 46.6 gr | 86% | 34,606 psi | 72% | 3392 fps | 95.4% |
| Alliant AR-Comp | <<locked>> | 80% | 35,534 psi | 74% | 3465 fps | 99.7% |
| Alliant AR-Comp | <<locked>> | 80% | 34,577 psi | 72% | 3442 fps | 99.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 24,787 psi | 51% | 2267 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 24,526 psi | 51% | 2264 fps | 100% |
| IMR 3031 | <<locked>> | 80% | 33,997 psi | 71% | 3425 fps | 96.7% |
| IMR 3031 | <<locked>> | 80% | 33,054 psi | 69% | 3399 fps | 96.3% |
| Lovex D073.6 | <<locked>> | 84% | 38,696 psi | 80% | 3497 fps | 95.6% |
| Lovex D073.6 | <<locked>> | 84% | 37,579 psi | 78% | 3471 fps | 95.2% |
| Norma 202 | <<locked>> | 82% | 36,883 psi | 77% | 3435 fps | 95.8% |
| Norma 202 | <<locked>> | 82% | 35,926 psi | 75% | 3412 fps | 95.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 24,889 psi | 52% | 2320 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 24,555 psi | 51% | 2316 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 40,074 psi | 83% | 3612 fps | 95.3% |
| Rottweil R 901 | <<locked>> | 80% | 38,159 psi | 79% | 3445 fps | 95.8% |
| Rottweil R 901 | <<locked>> | 80% | 36,970 psi | 77% | 3415 fps | 95.4% |
| Shooters World Match Rifle | <<locked>> | 84% | 38,696 psi | 80% | 3497 fps | 95.6% |
| Shooters World Match Rifle | <<locked>> | 84% | 37,579 psi | 78% | 3471 fps | 95.2% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 36,376 psi | 75% | 3340 fps | 95.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 35,476 psi | 74% | 3320 fps | 95.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 31,546 psi | 65% | 3199 fps | 95% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 32,982 psi | 68% | 3248 fps | 95.7% |
| Somchem S335 | <<locked>> | 80% | 35,810 psi | 74% | 3333 fps | 96.4% |
| Somchem S335 | <<locked>> | 80% | 34,867 psi | 72% | 3310 fps | 96.1% |
| Vihtavuori N130 | <<locked>> | 80% | 40,422 psi | 84% | 3471 fps | 99.6% |
| Vihtavuori N133 | <<locked>> | 80% | 36,303 psi | 75% | 3356 fps | 98.1% |
| Vihtavuori N133 | <<locked>> | 80% | 35,491 psi | 74% | 3340 fps | 97.9% |
| Vihtavuori N135 | 41.9 gr | 80% | 31,357 psi | 65% | 3281 fps | 96.7% |
| Vihtavuori N135 | 41.9 gr | 80% | 30,385 psi | 63% | 3258 fps | 96.3% |
| Vihtavuori N140 | <<locked>> | 82% | 34,969 psi | 73% | 3350 fps | 95.5% |
| Vihtavuori N140 | <<locked>> | 82% | 34,055 psi | 71% | 3327 fps | 95.2% |
| Vihtavuori N540 | <<locked>> | 84% | 36,216 psi | 75% | 3389 fps | 95.5% |
| Vihtavuori N540 | <<locked>> | 84% | 35,288 psi | 73% | 3363 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 121 powders for .257 Ackley Improved loaded with the .257 | 58gr | Peregrine VRG-2. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,701 fps; across all powders the maximum-charge window runs from 2,516 fps to 3,701 fps. Accurate 4350 gives the best case fill at 100 %, and 121 of the 121 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (332 MPa), the top charges use 69–90 %, leaving at least 10 % headroom. Accurate 4350, Hodgdon Hybrid 100V, Hodgdon Hybrid 100V 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. Accurate 4064, Vihtavuori N135, Accurate 2495 rank at the top here: for .257 Ackley Improved with the .257 | 58gr | Peregrine VRG-2 they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 4350, ADI AR 2206H, ADI AR 2206H burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.