Load Specifications
Load data in caliber .257 Ackley Improved with .257 | 117gr | Winchester Powerpoint bullet and 35 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Winchester StaBALL HD, Alliant Reloder-26 and Alliant Reloder-23.
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 3100 | <<locked>> | 94% | 43,033 psi | 89% | 2743 fps | 97.8% |
| Accurate 4350 | <<locked>> | 84% | 41,945 psi | 87% | 2740 fps | 98.9% |
| Alliant Reloder-16 | <<locked>> | 86% | 43,352 psi | 90% | 2808 fps | 99.4% |
| Alliant Reloder-17 | <<locked>> | 82% | 43,236 psi | 90% | 2818 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 94% | 40,915 psi | 85% | 2772 fps | 99.8% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 43,207 psi | 90% | 2848 fps | 98.6% |
| Alliant Reloder-26 | <<locked>> | 92% | 42,699 psi | 89% | 2877 fps | 99% |
| Bofors RP7 | <<locked>> | 82% | 43,352 psi | 90% | 2697 fps | 96.3% |
| Hodgdon H414 | <<locked>> | 82% | 41,263 psi | 86% | 2730 fps | 96.4% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 43,352 psi | 90% | 2743 fps | 99.9% |
| Hodgdon Superformance | <<locked>> | 84% | 43,265 psi | 90% | 2805 fps | 96.6% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,361 psi | 75% | 1824 fps | 100% |
| IMR 4831 | <<locked>> | 86% | 42,757 psi | 89% | 2740 fps | 99.1% |
| Lovex S065 | <<locked>> | 82% | 42,293 psi | 88% | 2677 fps | 97.9% |
| Lovex S070 | <<locked>> | 84% | 42,917 psi | 89% | 2710 fps | 97% |
| Lovex S071 | <<locked>> | 98% | 41,336 psi | 86% | 2710 fps | 97.4% |
| Norma MRP | <<locked>> | 92% | 42,453 psi | 88% | 2835 fps | 96.6% |
| Norma URP | <<locked>> | 84% | 41,437 psi | 86% | 2730 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 86% | 43,221 psi | 90% | 2779 fps | 97.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,912 psi | 77% | 1867 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 41,800 psi | 87% | 2759 fps | 98.6% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 43,424 psi | 90% | 2831 fps | 98.8% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 42,221 psi | 88% | 2861 fps | 96.6% |
| Rottweil R 907 | <<locked>> | 82% | 43,352 psi | 90% | 2697 fps | 96.3% |
| Shooters World Long Rifle | <<locked>> | 82% | 42,293 psi | 88% | 2677 fps | 97.9% |
| Shooters World SW4350 | <<locked>> | 84% | 42,917 psi | 89% | 2710 fps | 97% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 41,495 psi | 86% | 2621 fps | 96.5% |
| Somchem S365 | <<locked>> | 88% | 43,221 psi | 90% | 2799 fps | 100% |
| Somchem S385 | <<locked>> | 90% | 42,612 psi | 88% | 2733 fps | 96.1% |
| Vihtavuori N160 | <<locked>> | 84% | 43,105 psi | 89% | 2730 fps | 99% |
| Vihtavuori N550 | <<locked>> | 84% | 42,395 psi | 88% | 2730 fps | 98.7% |
| Vihtavuori N555 | <<locked>> | 92% | 42,888 psi | 89% | 2799 fps | 99.4% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 42,409 psi | 88% | 2700 fps | 99.9% |
| Winchester 760 | <<locked>> | 82% | 41,263 psi | 86% | 2730 fps | 96.4% |
| Winchester StaBALL HD | <<locked>> | 98% | 41,800 psi | 87% | 2923 fps | 100% |
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 3100 | <<locked>> | 88% | 35,259 psi | 73% | 2575 fps | 95.5% |
| Accurate 4350 | <<locked>> | 80% | 36,637 psi | 76% | 2625 fps | 97.7% |
| Alliant Reloder-16 | <<locked>> | 80% | 35,766 psi | 74% | 2631 fps | 97.7% |
| Alliant Reloder-17 | <<locked>> | 80% | 40,509 psi | 84% | 2766 fps | 99.8% |
| Alliant Reloder-23 | 40.2 gr | 80% | 26,223 psi | 54% | 2379 fps | 95% |
| Alliant Reloder-25 | <<locked>> | 92% | 33,707 psi | 70% | 2615 fps | 95.3% |
| Alliant Reloder-26 | 46.3 gr | 84% | 31,908 psi | 66% | 2608 fps | 95.4% |
| Bofors RP7 | <<locked>> | 80% | 40,727 psi | 84% | 2641 fps | 95.5% |
| Hodgdon H414 | <<locked>> | 80% | 38,450 psi | 80% | 2667 fps | 95.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 33,199 psi | 69% | 2526 fps | 98.3% |
| Hodgdon Superformance | <<locked>> | 82% | 40,379 psi | 84% | 2740 fps | 95.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,050 psi | 56% | 1627 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 35,215 psi | 73% | 2575 fps | 97.3% |
| Lovex S065 | <<locked>> | 80% | 39,755 psi | 82% | 2625 fps | 97.2% |
| Lovex S070 | <<locked>> | 80% | 37,884 psi | 79% | 2602 fps | 95.5% |
| Lovex S071 | <<locked>> | 94% | 36,201 psi | 75% | 2598 fps | 95.8% |
| Norma MRP | <<locked>> | 90% | 39,566 psi | 82% | 2772 fps | 95.7% |
| Norma URP | <<locked>> | 80% | 36,376 psi | 75% | 2618 fps | 97.5% |
| Ramshot Hunter | <<locked>> | 80% | 35,302 psi | 73% | 2602 fps | 95.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,630 psi | 57% | 1670 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 36,216 psi | 75% | 2638 fps | 97.2% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 35,244 psi | 73% | 2638 fps | 96.4% |
| ReloadSwiss RS 76 | <<locked>> | 98% | 39,349 psi | 82% | 2792 fps | 95.3% |
| Rottweil R 907 | <<locked>> | 80% | 40,727 psi | 84% | 2641 fps | 95.5% |
| Shooters World Long Rifle | <<locked>> | 80% | 39,755 psi | 82% | 2625 fps | 97.2% |
| Shooters World SW4350 | <<locked>> | 80% | 37,884 psi | 79% | 2602 fps | 95.5% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 38,711 psi | 80% | 2562 fps | 95.6% |
| Somchem S365 | <<locked>> | 80% | 32,793 psi | 68% | 2572 fps | 99.3% |
| Somchem S385 | <<locked>> | 88% | 40,016 psi | 83% | 2677 fps | 95.3% |
| Vihtavuori N160 | <<locked>> | 80% | 37,913 psi | 79% | 2621 fps | 97.9% |
| Vihtavuori N550 | <<locked>> | 80% | 37,159 psi | 77% | 2618 fps | 97.5% |
| Vihtavuori N555 | <<locked>> | 80% | 28,747 psi | 60% | 2461 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 37,043 psi | 77% | 2592 fps | 99.4% |
| Winchester 760 | <<locked>> | 80% | 38,682 psi | 80% | 2674 fps | 95.5% |
| Winchester StaBALL HD | 44.5 gr | 84% | 26,266 psi | 54% | 2461 fps | 95.7% |
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 35 powders for .257 Ackley Improved loaded with the .257 | 117gr | Winchester Powerpoint. Winchester StaBALL HD delivers the highest muzzle velocity at 2,923 fps; across all powders the maximum-charge window runs from 1,824 fps to 2,923 fps. Alliant Reloder-25 gives the best case fill at 100 %, and 35 of the 35 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (332 MPa), the top charges use 75–90 %, leaving at least 10 % headroom. The 117.0 gr projectile in 0.257" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-25, 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. Winchester StaBALL HD, Alliant Reloder-26, Alliant Reloder-23 rank at the top here: for .257 Ackley Improved with the .257 | 117gr | Winchester Powerpoint 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.