Load Specifications
Bullet:.257 | 117gr | Hornady SST
Bullet Manufacturer:Hornady
Bullet Weight:117 gr
Bullet Diameter:0.257"
Bullet Length:<<locked>>
Caliber:.25 WSSM load data
Case Length (l3):1.67"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:54.3 Grains of Water
Primer Size:Large Rifle (LR)
Barrel Length:24"
Max. allowed Pressure:63,817 psi
Recommended Twist Rate:1:11.0
Load data in caliber .25 WSSM with .257 | 117gr | Hornady SST bullet and 99 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-17, ReloadSwiss RS 60 and ReloadSwiss RS 70.
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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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 2015 | <<locked>> | 84% | 57,261 psi | 90% | 2789 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 56,463 psi | 88% | 2818 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 54,476 psi | 85% | 2835 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 55,317 psi | 87% | 2825 fps | 97.5% |
| Accurate 3100ᴾ | <<locked>> | 100% | 43,613 psi | 68% | 2726 fps | 97% |
| Accurate 4064 | <<locked>> | 90% | 56,536 psi | 89% | 2867 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 56,797 psi | 89% | 2963 fps | 99.9% |
| ADI AR 2206H | <<locked>> | 86% | 56,652 psi | 89% | 2904 fps | 100% |
| ADI AR 2208 | <<locked>> | 92% | 57,711 psi | 90% | 2904 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 84% | 55,535 psi | 87% | 2851 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 56,449 psi | 88% | 2815 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 56,246 psi | 88% | 3022 fps | 100% |
| Alliant Power Pro Varmintᴾ | <<locked>> | 100% | 51,024 psi | 80% | 2877 fps | 95.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 54,302 psi | 85% | 2871 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 88% | 54,955 psi | 86% | 2894 fps | 99.9% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 57,508 psi | 90% | 3015 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 94% | 55,085 psi | 86% | 2995 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 41,394 psi | 65% | 2756 fps | 99.4% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 46,383 psi | 73% | 2923 fps | 99% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 56,463 psi | 88% | 2917 fps | 99.9% |
| Bofors RP3 | <<locked>> | 90% | 54,984 psi | 86% | 2887 fps | 100% |
| Bofors RP7 | <<locked>> | 94% | 54,984 psi | 86% | 2861 fps | 97.7% |
| Hodgdon Benchmark | <<locked>> | 84% | 57,014 psi | 89% | 2828 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 84% | 54,868 psi | 86% | 2877 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 57,130 psi | 90% | 2982 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 55,622 psi | 87% | 2900 fps | 99.6% |
| Hodgdon H414 | <<locked>> | 96% | 55,666 psi | 87% | 2956 fps | 98.4% |
| Hodgdon H4350 | <<locked>> | 94% | 56,014 psi | 88% | 2917 fps | 97.3% |
| Hodgdon H4895 | <<locked>> | 86% | 57,232 psi | 90% | 2910 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 53,838 psi | 84% | 2887 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 56,710 psi | 89% | 2943 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 56,014 psi | 88% | 2992 fps | 98.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,665 psi | 56% | 1759 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 54,636 psi | 86% | 2858 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 57,479 psi | 90% | 2887 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 57,159 psi | 90% | 2884 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 88% | 57,072 psi | 89% | 2867 fps | 98.5% |
| IMR 4350 | <<locked>> | 98% | 55,201 psi | 87% | 2887 fps | 97.8% |
| IMR 4451 Enduron | <<locked>> | 94% | 56,913 psi | 89% | 2894 fps | 98.4% |
| IMR 4831ᴾ | <<locked>> | 100% | 57,130 psi | 90% | 2953 fps | 99.9% |
| IMR 4895 | <<locked>> | 88% | 56,333 psi | 88% | 2927 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 55,535 psi | 87% | 2851 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 56,347 psi | 88% | 2871 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 55,782 psi | 87% | 2825 fps | 100% |
| Lovex S062 | <<locked>> | 90% | 57,130 psi | 90% | 2881 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 56,144 psi | 88% | 2881 fps | 99.2% |
| Lovex S070 | <<locked>> | 98% | 57,334 psi | 90% | 2923 fps | 98.7% |
| Norma 201 | <<locked>> | 86% | 55,143 psi | 86% | 2841 fps | 100% |
| Norma 202 | <<locked>> | 86% | 55,709 psi | 87% | 2841 fps | 100% |
| Norma 203B | <<locked>> | 90% | 57,682 psi | 90% | 2933 fps | 100% |
| Norma 204 | <<locked>> | 98% | 55,985 psi | 88% | 2940 fps | 96.7% |
| Norma MRPᴾ | <<locked>> | 100% | 46,195 psi | 72% | 2877 fps | 96.5% |
| Norma URP | <<locked>> | 98% | 55,463 psi | 87% | 2946 fps | 99.8% |
| Ramshot Big Game | <<locked>> | 88% | 54,418 psi | 85% | 2904 fps | 100% |
| Ramshot Hunter | <<locked>> | 98% | 54,215 psi | 85% | 2943 fps | 98.9% |
| Ramshot TAC | <<locked>> | 84% | 55,608 psi | 87% | 2867 fps | 99.3% |
| Ramshot Wild Boar | <<locked>> | 84% | 55,608 psi | 87% | 2890 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 56,376 psi | 88% | 2851 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,216 psi | 57% | 1801 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 56,028 psi | 88% | 2884 fps | 98.8% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 55,259 psi | 87% | 2959 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 54,955 psi | 86% | 2995 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 56,463 psi | 88% | 2982 fps | 99.8% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 55,492 psi | 87% | 3009 fps | 99.7% |
| Rottweil R 901 | <<locked>> | 84% | 56,289 psi | 88% | 2822 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 55,999 psi | 88% | 2844 fps | 100% |
| Rottweil R 903 | <<locked>> | 92% | 54,781 psi | 86% | 2877 fps | 100% |
| Rottweil R 907 | <<locked>> | 94% | 54,984 psi | 86% | 2861 fps | 97.7% |
| Shooters World Long Rifle | <<locked>> | 96% | 56,144 psi | 88% | 2881 fps | 99.2% |
| Shooters World Match Rifle | <<locked>> | 86% | 56,347 psi | 88% | 2871 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 57,130 psi | 90% | 2881 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 57,334 psi | 90% | 2923 fps | 98.7% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 56,521 psi | 89% | 2940 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 54,143 psi | 85% | 2844 fps | 99.4% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 54,868 psi | 86% | 2867 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 56,753 psi | 89% | 2779 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 56,898 psi | 89% | 2776 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 56,724 psi | 89% | 2841 fps | 98.4% |
| Somchem S321 | <<locked>> | 82% | 56,840 psi | 89% | 2881 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 55,927 psi | 88% | 2772 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 57,537 psi | 90% | 2890 fps | 100% |
| Somchem S355 | <<locked>> | 92% | 55,245 psi | 87% | 2877 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 53,447 psi | 84% | 2943 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 49,472 psi | 78% | 2825 fps | 96.7% |
| Vihtavuori N130 | <<locked>> | 82% | 56,391 psi | 88% | 2740 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 57,029 psi | 89% | 2762 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 55,579 psi | 87% | 2802 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 56,275 psi | 88% | 2818 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 56,536 psi | 89% | 2854 fps | 100% |
| Vihtavuori N160 | <<locked>> | 96% | 54,476 psi | 85% | 2890 fps | 99.7% |
| Vihtavuori N530 | <<locked>> | 84% | 55,999 psi | 88% | 2848 fps | 100% |
| Vihtavuori N540 | <<locked>> | 88% | 54,462 psi | 85% | 2818 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 56,927 psi | 89% | 2946 fps | 99.8% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 45,745 psi | 72% | 2831 fps | 99.3% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 54,288 psi | 85% | 2864 fps | 100% |
| Winchester 748 | <<locked>> | 84% | 55,927 psi | 88% | 2894 fps | 100% |
| Winchester 760 | <<locked>> | 96% | 55,666 psi | 87% | 2956 fps | 98.4% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 37,014 psi | 58% | 2766 fps | 99.5% |
| Winchester StaBALL Match | <<locked>> | 86% | 55,042 psi | 86% | 2881 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 2015 | <<locked>> | 80% | 50,691 psi | 79% | 2697 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 43,569 psi | 68% | 2628 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 50,691 psi | 79% | 2782 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 45,498 psi | 71% | 2657 fps | 95.4% |
| Accurate 3100 | <<locked>> | 96% | 37,985 psi | 60% | 2615 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 41,220 psi | 65% | 2628 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 32,605 psi | 51% | 2507 fps | 95.3% |
| ADI AR 2206H | <<locked>> | 80% | 46,920 psi | 74% | 2743 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 80% | 39,740 psi | 62% | 2589 fps | 98.1% |
| ADI Benchmark 8208 | <<locked>> | 80% | 48,965 psi | 77% | 2746 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 49,647 psi | 78% | 2726 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 42,757 psi | 67% | 2779 fps | 98.7% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 47,863 psi | 75% | 2822 fps | 95.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 39,653 psi | 62% | 2615 fps | 99.2% |
| Alliant Reloder-15 | <<locked>> | 80% | 42,540 psi | 67% | 2680 fps | 98.8% |
| Alliant Reloder-16 | <<locked>> | 82% | 32,735 psi | 51% | 2516 fps | 95.4% |
| Alliant Reloder-17 | 37.6 gr | 80% | 34,229 psi | 54% | 2585 fps | 97.8% |
| Alliant Reloder-23 | <<locked>> | 88% | 28,471 psi | 45% | 2425 fps | 95.1% |
| Alliant Reloder-26 | <<locked>> | 92% | 35,099 psi | 55% | 2664 fps | 95.6% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 46,166 psi | 72% | 2749 fps | 99% |
| Bofors RP3 | <<locked>> | 80% | 39,537 psi | 62% | 2621 fps | 99.3% |
| Bofors RP7 | <<locked>> | 88% | 45,440 psi | 71% | 2697 fps | 95.7% |
| Hodgdon Benchmark | <<locked>> | 80% | 50,401 psi | 79% | 2730 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 47,979 psi | 75% | 2769 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 80% | 53,156 psi | 83% | 2923 fps | 99.9% |
| Hodgdon H380 | <<locked>> | 80% | 40,292 psi | 63% | 2628 fps | 97.2% |
| Hodgdon H414 | <<locked>> | 88% | 42,656 psi | 67% | 2726 fps | 95.7% |
| Hodgdon H4350 | <<locked>> | 88% | 46,311 psi | 73% | 2749 fps | 95.1% |
| Hodgdon H4895 | <<locked>> | 80% | 47,355 psi | 74% | 2756 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 28,253 psi | 44% | 2365 fps | 95.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 43,482 psi | 68% | 2726 fps | 99.7% |
| Hodgdon Superformance | <<locked>> | 90% | 45,440 psi | 71% | 2808 fps | 95.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,629 psi | 42% | 1572 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 45,455 psi | 71% | 2707 fps | 99.7% |
| IMR 3031 | <<locked>> | 80% | 47,297 psi | 74% | 2743 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 41,742 psi | 65% | 2625 fps | 98.7% |
| IMR 4166 Enduron | <<locked>> | 80% | 44,135 psi | 69% | 2644 fps | 95.9% |
| IMR 4350 | <<locked>> | 90% | 42,902 psi | 67% | 2671 fps | 95% |
| IMR 4451 Enduron | <<locked>> | 84% | 41,698 psi | 65% | 2625 fps | 95.1% |
| IMR 4831 | <<locked>> | 84% | 33,692 psi | 53% | 2516 fps | 95.8% |
| IMR 4895 | <<locked>> | 80% | 43,613 psi | 68% | 2710 fps | 99.3% |
| IMR 8208 XBR | <<locked>> | 80% | 48,965 psi | 77% | 2746 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 46,369 psi | 73% | 2723 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 46,586 psi | 73% | 2674 fps | 99.6% |
| Lovex S062 | <<locked>> | 80% | 41,829 psi | 66% | 2628 fps | 99.7% |
| Lovex S065 | <<locked>> | 82% | 36,680 psi | 57% | 2523 fps | 95.2% |
| Lovex S070 | <<locked>> | 88% | 41,858 psi | 66% | 2654 fps | 95.6% |
| Norma 201 | <<locked>> | 80% | 45,861 psi | 72% | 2690 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 46,296 psi | 73% | 2697 fps | 100% |
| Norma 203B | <<locked>> | 80% | 41,930 psi | 66% | 2667 fps | 99.1% |
| Norma 204 | <<locked>> | 94% | 48,791 psi | 76% | 2818 fps | 95.1% |
| Norma MRP | <<locked>> | 98% | 43,323 psi | 68% | 2818 fps | 95.6% |
| Norma URP | <<locked>> | 82% | 32,909 psi | 52% | 2510 fps | 95.2% |
| Ramshot Big Game | <<locked>> | 80% | 41,481 psi | 65% | 2680 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 88% | 39,146 psi | 61% | 2661 fps | 95.5% |
| Ramshot TAC | <<locked>> | 80% | 48,907 psi | 77% | 2759 fps | 98.4% |
| Ramshot Wild Boar | <<locked>> | 80% | 48,399 psi | 76% | 2776 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 80% | 52,692 psi | 83% | 2795 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,934 psi | 42% | 1608 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 40,408 psi | 63% | 2605 fps | 95.6% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 45,223 psi | 71% | 2792 fps | 99.2% |
| ReloadSwiss RS 60 | 37.6 gr | 80% | 36,405 psi | 57% | 2654 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 34,650 psi | 54% | 2579 fps | 95.7% |
| ReloadSwiss RS 70 | 41.1 gr | 86% | 36,956 psi | 58% | 2644 fps | 95.7% |
| Rottweil R 901 | <<locked>> | 80% | 49,937 psi | 78% | 2730 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 43,714 psi | 69% | 2644 fps | 99.8% |
| Rottweil R 903 | <<locked>> | 80% | 37,130 psi | 58% | 2566 fps | 98.7% |
| Rottweil R 907 | <<locked>> | 88% | 45,440 psi | 71% | 2697 fps | 95.7% |
| Shooters World Long Rifle | <<locked>> | 82% | 36,680 psi | 57% | 2523 fps | 95.2% |
| Shooters World Match Rifle | <<locked>> | 80% | 46,369 psi | 73% | 2723 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 41,829 psi | 66% | 2628 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 88% | 41,858 psi | 66% | 2654 fps | 95.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 38,174 psi | 60% | 2618 fps | 98.3% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 47,326 psi | 74% | 2733 fps | 98.6% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 45,484 psi | 71% | 2713 fps | 99.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 46,963 psi | 74% | 2638 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 39,262 psi | 62% | 2503 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 41,017 psi | 64% | 2572 fps | 95.1% |
| Somchem S321 | <<locked>> | 80% | 52,997 psi | 83% | 2825 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 46,760 psi | 73% | 2641 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 46,963 psi | 74% | 2726 fps | 99.6% |
| Somchem S355 | <<locked>> | 80% | 37,826 psi | 59% | 2569 fps | 98.6% |
| Somchem S365 | <<locked>> | 80% | 27,644 psi | 43% | 2405 fps | 96.7% |
| Somchem S385 | <<locked>> | 96% | 43,410 psi | 68% | 2717 fps | 95.1% |
| Vihtavuori N130 | <<locked>> | 80% | 52,910 psi | 83% | 2690 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 47,369 psi | 74% | 2628 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 43,250 psi | 68% | 2621 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 43,859 psi | 69% | 2631 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 36,027 psi | 56% | 2503 fps | 99.2% |
| Vihtavuori N160 | <<locked>> | 82% | 34,330 psi | 54% | 2510 fps | 95.7% |
| Vihtavuori N530 | <<locked>> | 80% | 49,197 psi | 77% | 2746 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 42,366 psi | 66% | 2625 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 33,852 psi | 53% | 2513 fps | 95.3% |
| Vihtavuori N555 | <<locked>> | 88% | 30,705 psi | 48% | 2500 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 31,807 psi | 50% | 2431 fps | 97.1% |
| Winchester 748 | <<locked>> | 80% | 49,182 psi | 77% | 2792 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 42,656 psi | 67% | 2726 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 92% | 28,572 psi | 45% | 2503 fps | 95.7% |
| Winchester StaBALL Match | <<locked>> | 80% | 44,817 psi | 70% | 2713 fps | 99.7% |
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 99 powders for .25 WSSM loaded with the .257 | 117gr | Hornady SST. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,022 fps; across all powders the maximum-charge window runs from 1,759 fps to 3,022 fps. Accurate 3100 gives the best case fill at 100 %, and 99 of the 99 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 117.0 gr projectile in 0.257" calls for a 1:11.0 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Power Pro Varmint, Alliant Reloder-16 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. Alliant Reloder-17, ReloadSwiss RS 60, ReloadSwiss RS 70 rank at the top here: for .25 WSSM with the .257 | 117gr | Hornady SST 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.