Load Specifications
Load data in caliber .25 WSSM with .257 | 115gr | Barnes X S bullet and 97 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>> | 82% | 55,550 psi | 87% | 2759 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 55,680 psi | 87% | 2799 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 55,912 psi | 88% | 2848 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 56,159 psi | 88% | 2825 fps | 97.2% |
| Accurate 3100ᴾ | <<locked>> | 100% | 45,295 psi | 71% | 2746 fps | 96.9% |
| Accurate 4064 | <<locked>> | 88% | 55,317 psi | 87% | 2841 fps | 100% |
| Accurate 4350 | <<locked>> | 96% | 54,099 psi | 85% | 2917 fps | 99.6% |
| ADI AR 2206H | <<locked>> | 86% | 57,595 psi | 90% | 2907 fps | 100% |
| ADI AR 2208 | <<locked>> | 90% | 54,998 psi | 86% | 2854 fps | 99.8% |
| ADI Benchmark 8208 | <<locked>> | 84% | 56,202 psi | 88% | 2854 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 57,522 psi | 90% | 2828 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 57,159 psi | 90% | 3031 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 55,405 psi | 87% | 2884 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 88% | 56,043 psi | 88% | 2907 fps | 99.9% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 57,711 psi | 90% | 3015 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 94% | 55,941 psi | 88% | 3005 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 42,496 psi | 67% | 2769 fps | 99.3% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 47,413 psi | 74% | 2933 fps | 98.8% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 57,029 psi | 89% | 2920 fps | 99.8% |
| Bofors RP3 | <<locked>> | 90% | 56,623 psi | 89% | 2904 fps | 100% |
| Bofors RP7 | <<locked>> | 94% | 55,985 psi | 88% | 2867 fps | 97.4% |
| Hodgdon Benchmark | <<locked>> | 82% | 54,578 psi | 86% | 2789 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 84% | 56,101 psi | 88% | 2890 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 57,087 psi | 89% | 2913 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 96% | 56,159 psi | 88% | 2959 fps | 98.1% |
| Hodgdon H4350 | <<locked>> | 94% | 56,623 psi | 89% | 2917 fps | 96.9% |
| Hodgdon H4895 | <<locked>> | 84% | 54,737 psi | 86% | 2867 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 54,679 psi | 86% | 2897 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 57,711 psi | 90% | 2953 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 56,840 psi | 89% | 2995 fps | 97.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,940 psi | 56% | 1759 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 55,695 psi | 87% | 2867 fps | 100% |
| IMR 3031 | <<locked>> | 84% | 54,911 psi | 86% | 2851 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 54,447 psi | 85% | 2838 fps | 99.8% |
| IMR 4166 Enduron | <<locked>> | 88% | 57,522 psi | 90% | 2864 fps | 98.2% |
| IMR 4350 | <<locked>> | 98% | 55,985 psi | 88% | 2890 fps | 97.5% |
| IMR 4451 Enduron | <<locked>> | 94% | 57,479 psi | 90% | 2894 fps | 98.1% |
| IMR 4831 | <<locked>> | 98% | 54,317 psi | 85% | 2904 fps | 99.6% |
| IMR 4895 | <<locked>> | 88% | 57,464 psi | 90% | 2936 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 56,202 psi | 88% | 2854 fps | 100% |
| Lovex D073.6 | <<locked>> | 84% | 54,317 psi | 85% | 2838 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 56,753 psi | 89% | 2831 fps | 100% |
| Lovex S062 | <<locked>> | 88% | 54,882 psi | 86% | 2841 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 57,246 psi | 90% | 2890 fps | 99.1% |
| Lovex S070 | <<locked>> | 96% | 55,143 psi | 86% | 2881 fps | 98% |
| Norma 201 | <<locked>> | 86% | 56,884 psi | 89% | 2858 fps | 100% |
| Norma 202 | <<locked>> | 86% | 57,058 psi | 89% | 2854 fps | 100% |
| Norma 203B | <<locked>> | 88% | 55,317 psi | 87% | 2894 fps | 100% |
| Norma 204 | <<locked>> | 98% | 56,492 psi | 89% | 2936 fps | 96.3% |
| Norma MRPᴾ | <<locked>> | 100% | 47,413 psi | 74% | 2890 fps | 96.2% |
| Norma URP | <<locked>> | 98% | 55,999 psi | 88% | 2949 fps | 99.7% |
| Ramshot Big Game | <<locked>> | 88% | 55,477 psi | 87% | 2917 fps | 100% |
| Ramshot Hunter | <<locked>> | 98% | 54,839 psi | 86% | 2946 fps | 98.6% |
| Ramshot TAC | <<locked>> | 84% | 56,637 psi | 89% | 2877 fps | 99.1% |
| Ramshot Wild Boar | <<locked>> | 84% | 56,217 psi | 88% | 2894 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 57,246 psi | 90% | 2858 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,608 psi | 57% | 1801 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 56,942 psi | 89% | 2890 fps | 98.6% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 56,188 psi | 88% | 2969 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 55,666 psi | 87% | 3005 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 56,855 psi | 89% | 2986 fps | 99.7% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 56,202 psi | 88% | 3015 fps | 99.5% |
| Rottweil R 901 | <<locked>> | 82% | 55,129 psi | 86% | 2795 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 57,363 psi | 90% | 2858 fps | 100% |
| Rottweil R 903 | <<locked>> | 92% | 56,463 psi | 88% | 2894 fps | 100% |
| Rottweil R 907 | <<locked>> | 94% | 55,985 psi | 88% | 2867 fps | 97.4% |
| Shooters World Long Rifle | <<locked>> | 96% | 57,246 psi | 90% | 2890 fps | 99.1% |
| Shooters World Match Rifle | <<locked>> | 84% | 54,317 psi | 85% | 2838 fps | 100% |
| Shooters World Precision | <<locked>> | 88% | 54,882 psi | 86% | 2841 fps | 100% |
| Shooters World SW4350 | <<locked>> | 96% | 55,143 psi | 86% | 2881 fps | 98% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 57,232 psi | 90% | 2946 fps | 100% |
| SNPE Vectan SP 3 | <<locked>> | 84% | 54,389 psi | 85% | 2723 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 55,521 psi | 87% | 2858 fps | 99.3% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 55,796 psi | 87% | 2877 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 54,244 psi | 85% | 2740 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 57,696 psi | 90% | 2782 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 57,537 psi | 90% | 2841 fps | 98.1% |
| Somchem S335 | <<locked>> | 86% | 57,377 psi | 90% | 2789 fps | 100% |
| Somchem S341 | <<locked>> | 84% | 54,723 psi | 86% | 2844 fps | 99.9% |
| Somchem S355 | <<locked>> | 92% | 56,231 psi | 88% | 2887 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 54,128 psi | 85% | 2956 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 50,560 psi | 79% | 2838 fps | 96.4% |
| Vihtavuori N130 | <<locked>> | 82% | 57,261 psi | 90% | 2746 fps | 100% |
| Vihtavuori N133 | <<locked>> | 84% | 54,389 psi | 85% | 2723 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 57,014 psi | 89% | 2818 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 57,174 psi | 90% | 2828 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 57,464 psi | 90% | 2861 fps | 100% |
| Vihtavuori N160 | <<locked>> | 96% | 54,926 psi | 86% | 2890 fps | 99.5% |
| Vihtavuori N530 | <<locked>> | 84% | 56,840 psi | 89% | 2854 fps | 100% |
| Vihtavuori N540 | <<locked>> | 88% | 55,680 psi | 87% | 2831 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 57,682 psi | 90% | 2953 fps | 99.7% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 46,891 psi | 73% | 2848 fps | 99.2% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 54,969 psi | 86% | 2867 fps | 100% |
| Winchester 748 | <<locked>> | 84% | 56,782 psi | 89% | 2904 fps | 100% |
| Winchester 760 | <<locked>> | 96% | 56,521 psi | 89% | 2963 fps | 98.2% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 38,551 psi | 60% | 2792 fps | 99.5% |
| Winchester StaBALL Match | <<locked>> | 86% | 55,724 psi | 87% | 2884 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% | 52,518 psi | 82% | 2717 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 46,340 psi | 73% | 2661 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 52,489 psi | 82% | 2799 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 46,760 psi | 73% | 2667 fps | 95.2% |
| Accurate 3100 | <<locked>> | 96% | 39,711 psi | 62% | 2638 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 43,743 psi | 69% | 2657 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 34,577 psi | 54% | 2539 fps | 95.6% |
| ADI AR 2206H | <<locked>> | 80% | 48,211 psi | 76% | 2756 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 80% | 41,176 psi | 65% | 2608 fps | 98% |
| ADI Benchmark 8208 | <<locked>> | 80% | 50,082 psi | 78% | 2759 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 50,705 psi | 79% | 2736 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 43,685 psi | 68% | 2789 fps | 98.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 41,118 psi | 64% | 2635 fps | 99.2% |
| Alliant Reloder-15 | <<locked>> | 80% | 44,005 psi | 69% | 2700 fps | 98.7% |
| Alliant Reloder-16 | <<locked>> | 82% | 34,156 psi | 54% | 2543 fps | 95.4% |
| Alliant Reloder-17 | 36.5 gr | 80% | 35,810 psi | 56% | 2615 fps | 97.9% |
| Alliant Reloder-23 | <<locked>> | 88% | 30,182 psi | 47% | 2461 fps | 95.4% |
| Alliant Reloder-26 | <<locked>> | 92% | 36,637 psi | 57% | 2690 fps | 95.5% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 47,152 psi | 74% | 2759 fps | 98.8% |
| Bofors RP3 | <<locked>> | 80% | 41,510 psi | 65% | 2651 fps | 99.3% |
| Bofors RP7 | <<locked>> | 88% | 47,137 psi | 74% | 2717 fps | 95.6% |
| Hodgdon Benchmark | <<locked>> | 80% | 51,663 psi | 81% | 2743 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 49,226 psi | 77% | 2785 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 41,727 psi | 65% | 2644 fps | 97.2% |
| Hodgdon H414 | <<locked>> | 88% | 43,918 psi | 69% | 2743 fps | 95.5% |
| Hodgdon H4350 | <<locked>> | 90% | 50,401 psi | 79% | 2815 fps | 95.6% |
| Hodgdon H4895 | <<locked>> | 80% | 48,718 psi | 76% | 2769 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 29,921 psi | 47% | 2395 fps | 95.6% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 44,498 psi | 70% | 2740 fps | 99.7% |
| Hodgdon Superformance | <<locked>> | 90% | 46,398 psi | 73% | 2815 fps | 95.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,006 psi | 42% | 1572 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 46,456 psi | 73% | 2717 fps | 99.6% |
| IMR 3031 | <<locked>> | 80% | 48,515 psi | 76% | 2756 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 43,221 psi | 68% | 2641 fps | 98.6% |
| IMR 4166 Enduron | <<locked>> | 80% | 45,353 psi | 71% | 2654 fps | 95.7% |
| IMR 4350 | <<locked>> | 92% | 46,847 psi | 73% | 2736 fps | 95.5% |
| IMR 4451 Enduron | <<locked>> | 84% | 42,960 psi | 67% | 2638 fps | 95% |
| IMR 4831 | <<locked>> | 82% | 33,402 psi | 52% | 2497 fps | 95.2% |
| IMR 4895 | <<locked>> | 80% | 45,092 psi | 71% | 2730 fps | 99.3% |
| IMR 8208 XBR | <<locked>> | 80% | 50,082 psi | 78% | 2759 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 47,935 psi | 75% | 2740 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 47,543 psi | 75% | 2684 fps | 99.5% |
| Lovex S062 | <<locked>> | 80% | 43,453 psi | 68% | 2648 fps | 99.7% |
| Lovex S065 | <<locked>> | 82% | 38,464 psi | 60% | 2546 fps | 95.3% |
| Lovex S070 | <<locked>> | 88% | 43,410 psi | 68% | 2671 fps | 95.5% |
| Norma 201 | <<locked>> | 80% | 47,558 psi | 75% | 2710 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 47,645 psi | 75% | 2713 fps | 100% |
| Norma 203B | <<locked>> | 80% | 43,410 psi | 68% | 2687 fps | 99% |
| Norma 204 | <<locked>> | 96% | 53,026 psi | 83% | 2881 fps | 95.6% |
| Norma MRP | <<locked>> | 98% | 44,498 psi | 70% | 2831 fps | 95.3% |
| Norma URP | <<locked>> | 82% | 34,592 psi | 54% | 2539 fps | 95.4% |
| Ramshot Big Game | <<locked>> | 80% | 42,598 psi | 67% | 2694 fps | 98.8% |
| Ramshot Hunter | <<locked>> | 88% | 40,292 psi | 63% | 2674 fps | 95.3% |
| Ramshot TAC | <<locked>> | 80% | 49,937 psi | 78% | 2766 fps | 98.2% |
| Ramshot Wild Boar | <<locked>> | 80% | 49,719 psi | 78% | 2789 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 80% | 53,606 psi | 84% | 2802 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,383 psi | 43% | 1608 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 41,989 psi | 66% | 2625 fps | 95.5% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 46,209 psi | 72% | 2802 fps | 99% |
| ReloadSwiss RS 60 | 36.5 gr | 80% | 37,898 psi | 59% | 2677 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 82% | 34,127 psi | 53% | 2552 fps | 95% |
| ReloadSwiss RS 70 | 39.8 gr | 86% | 38,203 psi | 60% | 2661 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 51,851 psi | 81% | 2746 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 45,411 psi | 71% | 2664 fps | 99.8% |
| Rottweil R 903 | <<locked>> | 80% | 39,102 psi | 61% | 2595 fps | 98.8% |
| Rottweil R 907 | <<locked>> | 88% | 47,137 psi | 74% | 2717 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 82% | 38,464 psi | 60% | 2546 fps | 95.3% |
| Shooters World Match Rifle | <<locked>> | 80% | 47,935 psi | 75% | 2740 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 43,453 psi | 68% | 2648 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 88% | 43,410 psi | 68% | 2671 fps | 95.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 39,334 psi | 62% | 2635 fps | 98.2% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 48,602 psi | 76% | 2641 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 48,704 psi | 76% | 2749 fps | 98.5% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 46,456 psi | 73% | 2723 fps | 99.4% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 48,399 psi | 76% | 2651 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 40,683 psi | 64% | 2523 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 42,511 psi | 67% | 2589 fps | 95% |
| Somchem S335 | <<locked>> | 80% | 48,153 psi | 75% | 2654 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 48,008 psi | 75% | 2736 fps | 99.5% |
| Somchem S355 | <<locked>> | 80% | 39,566 psi | 62% | 2595 fps | 98.7% |
| Somchem S365 | <<locked>> | 80% | 29,486 psi | 46% | 2444 fps | 97.1% |
| Somchem S385 | <<locked>> | 96% | 44,889 psi | 70% | 2733 fps | 95% |
| Vihtavuori N130 | <<locked>> | 80% | 54,172 psi | 85% | 2703 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 48,602 psi | 76% | 2641 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 44,991 psi | 71% | 2641 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 45,150 psi | 71% | 2648 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 37,666 psi | 59% | 2530 fps | 99.2% |
| Vihtavuori N160 | <<locked>> | 80% | 33,750 psi | 53% | 2484 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 50,372 psi | 79% | 2756 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 43,555 psi | 68% | 2638 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 35,389 psi | 55% | 2539 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 88% | 32,648 psi | 51% | 2543 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 33,257 psi | 52% | 2454 fps | 97.2% |
| Winchester 748 | <<locked>> | 80% | 50,067 psi | 78% | 2802 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 43,918 psi | 69% | 2743 fps | 95.5% |
| Winchester StaBALL HD | <<locked>> | 92% | 30,429 psi | 48% | 2543 fps | 96.1% |
| Winchester StaBALL Match | <<locked>> | 80% | 46,253 psi | 72% | 2733 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 97 powders for .25 WSSM loaded with the .257 | 115gr | Barnes X S. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,031 fps; across all powders the maximum-charge window runs from 1,759 fps to 3,031 fps. Accurate 3100 gives the best case fill at 100 %, and 97 of the 97 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 115.0 gr projectile in 0.257" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-16, Alliant Reloder-23 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 | 115gr | Barnes X S 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.