Load Specifications
Bullet:.257 | 100gr | Frontier BTSP
Bullet Manufacturer:Frontier Bullets
Bullet Weight:100 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:1:9.0
Load data in caliber .25 WSSM with .257 | 100gr | Frontier BTSP bullet and 99 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 60, Alliant Power Pro 2000-MR and ReloadSwiss RS 52.
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>> | 88% | 57,188 psi | 90% | 3005 fps | 100% |
| Accurate 2460 | <<locked>> | 84% | 55,869 psi | 88% | 3035 fps | 100% |
| Accurate 2495 | <<locked>> | 92% | 55,390 psi | 87% | 3025 fps | 100% |
| Accurate 2520 | <<locked>> | 86% | 54,070 psi | 85% | 3045 fps | 100% |
| Accurate 4064 | <<locked>> | 94% | 54,955 psi | 86% | 3064 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 50,981 psi | 80% | 3077 fps | 98.3% |
| Accurate LT-30 | <<locked>> | 82% | 56,144 psi | 88% | 2946 fps | 100% |
| Accurate LT-32 | <<locked>> | 82% | 56,550 psi | 89% | 2972 fps | 100% |
| ADI AR 2206H | <<locked>> | 90% | 56,391 psi | 88% | 3107 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 96% | 57,363 psi | 90% | 3097 fps | 99.4% |
| ADI AR 2219 | <<locked>> | 82% | 57,421 psi | 90% | 3074 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 88% | 55,463 psi | 87% | 3054 fps | 99.9% |
| Alliant AR-Comp | <<locked>> | 88% | 55,564 psi | 87% | 3035 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 84% | 57,058 psi | 89% | 3173 fps | 99.9% |
| Alliant Power Pro 2000-MR | <<locked>> | 92% | 55,941 psi | 88% | 3222 fps | 99.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 96% | 56,768 psi | 89% | 3117 fps | 99.9% |
| Alliant Reloder-10x | <<locked>> | 84% | 56,710 psi | 89% | 3012 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 94% | 57,537 psi | 90% | 3143 fps | 99.5% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 49,545 psi | 78% | 3077 fps | 98.3% |
| Alliant Reloder-17 | <<locked>> | 98% | 54,070 psi | 85% | 3186 fps | 99.8% |
| Baschieri & Pellagri 106 | <<locked>> | 82% | 55,608 psi | 87% | 2940 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 90% | 56,246 psi | 88% | 3114 fps | 99.1% |
| Bofors RP3 | <<locked>> | 94% | 53,954 psi | 85% | 3084 fps | 99.9% |
| Hodgdon Benchmark | <<locked>> | 88% | 57,421 psi | 90% | 3041 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 88% | 54,491 psi | 85% | 3084 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 86% | 56,420 psi | 88% | 3186 fps | 99.5% |
| Hodgdon H322 | <<locked>> | 84% | 56,130 psi | 88% | 3058 fps | 100% |
| Hodgdon H335 | <<locked>> | 84% | 57,522 psi | 90% | 3084 fps | 100% |
| Hodgdon H380 | <<locked>> | 94% | 55,100 psi | 86% | 3091 fps | 98.5% |
| Hodgdon H414ᴾ | <<locked>> | 100% | 54,114 psi | 85% | 3127 fps | 96.4% |
| Hodgdon H4895 | <<locked>> | 90% | 56,971 psi | 89% | 3117 fps | 99.9% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 45,629 psi | 72% | 2949 fps | 98.8% |
| Hodgdon LEVERevolution | <<locked>> | 92% | 56,130 psi | 88% | 3150 fps | 100% |
| Hodgdon Superformanceᴾ | <<locked>> | 100% | 55,898 psi | 88% | 3166 fps | 96% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,795 psi | 55% | 1880 fps | 100% |
| Hodgdon VARGET | <<locked>> | 90% | 54,549 psi | 85% | 3061 fps | 99.7% |
| IMR 3031 | <<locked>> | 90% | 56,231 psi | 88% | 3100 fps | 100% |
| IMR 4064 | <<locked>> | 94% | 56,681 psi | 89% | 3081 fps | 99.5% |
| IMR 4166 Enduron | <<locked>> | 92% | 57,058 psi | 89% | 3054 fps | 96.7% |
| IMR 4198 | <<locked>> | 84% | 56,869 psi | 89% | 2972 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 98% | 56,608 psi | 89% | 3077 fps | 96.6% |
| IMR 4831ᴾ | <<locked>> | 100% | 48,370 psi | 76% | 3012 fps | 97.9% |
| IMR 4895 | <<locked>> | 92% | 55,274 psi | 87% | 3120 fps | 99.6% |
| IMR 8208 XBR | <<locked>> | 88% | 55,463 psi | 87% | 3054 fps | 99.9% |
| Lovex D073.5 | <<locked>> | 84% | 55,637 psi | 87% | 3041 fps | 100% |
| Lovex D073.6 | <<locked>> | 90% | 55,883 psi | 88% | 3081 fps | 100% |
| Lovex S060 | <<locked>> | 90% | 56,144 psi | 88% | 3028 fps | 99.6% |
| Lovex S062 | <<locked>> | 94% | 56,289 psi | 88% | 3077 fps | 100% |
| Lovex S065ᴾ | <<locked>> | 100% | 55,390 psi | 87% | 3064 fps | 97.8% |
| Lovex S070ᴾ | <<locked>> | 100% | 52,837 psi | 83% | 3041 fps | 96.2% |
| Norma 201 | <<locked>> | 90% | 54,998 psi | 86% | 3048 fps | 99.9% |
| Norma 202 | <<locked>> | 90% | 55,376 psi | 87% | 3051 fps | 100% |
| Norma 203B | <<locked>> | 94% | 56,681 psi | 89% | 3127 fps | 99.7% |
| Norma URPᴾ | <<locked>> | 100% | 50,343 psi | 79% | 3064 fps | 98.1% |
| Ramshot Big Game | <<locked>> | 94% | 57,406 psi | 90% | 3156 fps | 99.7% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 49,443 psi | 77% | 3051 fps | 96.2% |
| Ramshot TAC | <<locked>> | 88% | 55,912 psi | 88% | 3068 fps | 98% |
| Ramshot Wild Boar | <<locked>> | 88% | 55,129 psi | 86% | 3087 fps | 99.5% |
| Ramshot X-Terminator | <<locked>> | 86% | 56,811 psi | 89% | 3058 fps | 99.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,215 psi | 55% | 1923 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 84% | 54,824 psi | 86% | 3035 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 94% | 55,767 psi | 87% | 3071 fps | 97.2% |
| ReloadSwiss RS 52 | <<locked>> | 90% | 54,418 psi | 85% | 3159 fps | 99.2% |
| ReloadSwiss RS 60 | <<locked>> | 98% | 57,711 psi | 90% | 3251 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 50,633 psi | 79% | 3097 fps | 98% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 50,995 psi | 80% | 3114 fps | 97.5% |
| Rottweil R 901 | <<locked>> | 88% | 55,782 psi | 87% | 3031 fps | 100% |
| Rottweil R 902 | <<locked>> | 92% | 55,419 psi | 87% | 3041 fps | 99.9% |
| Rottweil R 903 | <<locked>> | 98% | 57,174 psi | 90% | 3123 fps | 99.9% |
| Shooters World Long Rifleᴾ | <<locked>> | 100% | 55,390 psi | 87% | 3064 fps | 97.8% |
| Shooters World Match Rifle | <<locked>> | 90% | 55,883 psi | 88% | 3081 fps | 100% |
| Shooters World Precision | <<locked>> | 94% | 56,289 psi | 88% | 3077 fps | 100% |
| Shooters World SW4350ᴾ | <<locked>> | 100% | 52,837 psi | 83% | 3041 fps | 96.2% |
| Shooters World Tactical Rifle | <<locked>> | 82% | 54,752 psi | 86% | 3005 fps | 99.8% |
| SNPE Vectan SP 11 | <<locked>> | 96% | 55,608 psi | 87% | 3133 fps | 99.6% |
| SNPE Vectan SP 3 | <<locked>> | 84% | 57,711 psi | 90% | 3035 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 88% | 54,114 psi | 85% | 3041 fps | 98.2% |
| SNPE Vectan SP 9 | <<locked>> | 90% | 54,853 psi | 86% | 3074 fps | 99.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 90% | 56,811 psi | 89% | 2989 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 96% | 56,724 psi | 89% | 2982 fps | 100% |
| SNPE Vectan Tubal 7000ᴾ | <<locked>> | 100% | 56,391 psi | 88% | 3018 fps | 96.6% |
| Somchem S321 | <<locked>> | 86% | 56,927 psi | 89% | 3094 fps | 100% |
| Somchem S335 | <<locked>> | 90% | 55,985 psi | 88% | 2986 fps | 100% |
| Somchem S341 | <<locked>> | 90% | 57,522 psi | 90% | 3094 fps | 99.7% |
| Somchem S355 | <<locked>> | 98% | 57,377 psi | 90% | 3117 fps | 99.9% |
| Somchem S365ᴾ | <<locked>> | 100% | 44,788 psi | 70% | 3009 fps | 99.6% |
| Vihtavuori N130 | <<locked>> | 86% | 56,391 psi | 88% | 2953 fps | 100% |
| Vihtavuori N133 | <<locked>> | 90% | 56,884 psi | 89% | 2972 fps | 100% |
| Vihtavuori N135 | <<locked>> | 92% | 54,520 psi | 85% | 3009 fps | 100% |
| Vihtavuori N140 | <<locked>> | 92% | 55,927 psi | 88% | 3028 fps | 100% |
| Vihtavuori N150 | <<locked>> | 98% | 55,695 psi | 87% | 3048 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 53,069 psi | 83% | 3068 fps | 98.5% |
| Vihtavuori N530 | <<locked>> | 88% | 55,985 psi | 88% | 3054 fps | 100% |
| Vihtavuori N540 | <<locked>> | 94% | 57,682 psi | 90% | 3074 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 51,895 psi | 81% | 3064 fps | 98.2% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 53,911 psi | 84% | 3048 fps | 99.8% |
| Winchester 748 | <<locked>> | 88% | 55,637 psi | 87% | 3107 fps | 100% |
| Winchester 760ᴾ | <<locked>> | 100% | 54,491 psi | 85% | 3133 fps | 96.4% |
| Winchester StaBALL Match | <<locked>> | 90% | 54,389 psi | 85% | 3077 fps | 99.7% |
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% | 44,527 psi | 70% | 2808 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 48,631 psi | 76% | 2920 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 37,217 psi | 58% | 2717 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 43,947 psi | 69% | 2871 fps | 99.8% |
| Accurate 4064 | <<locked>> | 80% | 35,157 psi | 55% | 2697 fps | 99.3% |
| Accurate 4350 | <<locked>> | 92% | 38,276 psi | 60% | 2825 fps | 95.2% |
| Accurate LT-30 | <<locked>> | 80% | 52,997 psi | 83% | 2900 fps | 100% |
| Accurate LT-32 | <<locked>> | 80% | 53,388 psi | 84% | 2927 fps | 100% |
| ADI AR 2206H | <<locked>> | 80% | 41,147 psi | 64% | 2822 fps | 97.4% |
| ADI AR 2208 | <<locked>> | 82% | 37,231 psi | 58% | 2710 fps | 95.4% |
| ADI AR 2219 | <<locked>> | 80% | 53,708 psi | 84% | 3022 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 80% | 43,178 psi | 68% | 2838 fps | 98.8% |
| Alliant AR-Comp | <<locked>> | 80% | 42,598 psi | 67% | 2835 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 50,198 psi | 79% | 3054 fps | 99.4% |
| Alliant Power Pro 2000-MR | 38.5 gr | 82% | 39,711 psi | 62% | 2890 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 34,243 psi | 54% | 2677 fps | 96.3% |
| Alliant Reloder-10x | <<locked>> | 80% | 50,386 psi | 79% | 2917 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 36,956 psi | 58% | 2743 fps | 95.5% |
| Alliant Reloder-16 | <<locked>> | 92% | 38,812 psi | 61% | 2841 fps | 95.3% |
| Alliant Reloder-17 | <<locked>> | 84% | 33,663 psi | 53% | 2736 fps | 95.2% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 51,938 psi | 81% | 2887 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 39,943 psi | 63% | 2808 fps | 95.9% |
| Bofors RP3 | <<locked>> | 80% | 33,518 psi | 53% | 2671 fps | 96.2% |
| Hodgdon Benchmark | <<locked>> | 80% | 44,875 psi | 70% | 2828 fps | 99.4% |
| Hodgdon BL-C2 | <<locked>> | 80% | 41,640 psi | 65% | 2851 fps | 99% |
| Hodgdon CFE223 | <<locked>> | 80% | 45,455 psi | 71% | 2992 fps | 97.9% |
| Hodgdon H322 | <<locked>> | 80% | 49,066 psi | 77% | 2946 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 50,154 psi | 79% | 2972 fps | 100% |
| Hodgdon H380 | <<locked>> | 86% | 42,279 psi | 66% | 2851 fps | 95.8% |
| Hodgdon H414 | <<locked>> | 98% | 50,604 psi | 79% | 3064 fps | 95.6% |
| Hodgdon H4895 | <<locked>> | 80% | 41,452 psi | 65% | 2835 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 33,373 psi | 52% | 2671 fps | 95.2% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 37,144 psi | 58% | 2789 fps | 97.3% |
| Hodgdon Superformance | <<locked>> | 98% | 51,895 psi | 81% | 3097 fps | 95.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,034 psi | 41% | 1683 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 39,624 psi | 62% | 2776 fps | 97.5% |
| IMR 3031 | <<locked>> | 80% | 40,625 psi | 64% | 2838 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 36,521 psi | 57% | 2690 fps | 95.5% |
| IMR 4166 Enduron | <<locked>> | 88% | 50,604 psi | 79% | 2943 fps | 95.4% |
| IMR 4198 | <<locked>> | 80% | 50,488 psi | 79% | 2877 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 94% | 49,850 psi | 78% | 2959 fps | 95.1% |
| IMR 4831 | <<locked>> | 94% | 39,769 psi | 62% | 2841 fps | 95.8% |
| IMR 4895 | <<locked>> | 80% | 37,811 psi | 59% | 2776 fps | 96.5% |
| IMR 8208 XBR | <<locked>> | 80% | 43,178 psi | 68% | 2838 fps | 98.8% |
| Lovex D073.5 | <<locked>> | 80% | 48,457 psi | 76% | 2927 fps | 99.8% |
| Lovex D073.6 | <<locked>> | 80% | 39,624 psi | 62% | 2795 fps | 99.3% |
| Lovex S060 | <<locked>> | 80% | 41,437 psi | 65% | 2759 fps | 97.5% |
| Lovex S062 | <<locked>> | 80% | 36,434 psi | 57% | 2700 fps | 97.4% |
| Lovex S065 | <<locked>> | 92% | 43,468 psi | 68% | 2844 fps | 95.1% |
| Lovex S070 | <<locked>> | 98% | 49,516 psi | 78% | 2982 fps | 95.4% |
| Norma 201 | <<locked>> | 80% | 40,248 psi | 63% | 2776 fps | 98.3% |
| Norma 202 | <<locked>> | 80% | 40,393 psi | 63% | 2789 fps | 99.7% |
| Norma 203B | <<locked>> | 80% | 36,332 psi | 57% | 2733 fps | 96% |
| Norma URP | <<locked>> | 92% | 38,754 psi | 61% | 2828 fps | 95.1% |
| Ramshot Big Game | <<locked>> | 80% | 35,795 psi | 56% | 2740 fps | 95.5% |
| Ramshot Hunter | <<locked>> | 98% | 46,354 psi | 73% | 2989 fps | 95.4% |
| Ramshot TAC | <<locked>> | 80% | 42,960 psi | 67% | 2825 fps | 95.2% |
| Ramshot Wild Boar | <<locked>> | 80% | 42,351 psi | 66% | 2851 fps | 97.6% |
| Ramshot X-Terminator | <<locked>> | 80% | 46,499 psi | 73% | 2881 fps | 98.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,208 psi | 41% | 1722 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 48,138 psi | 75% | 2927 fps | 99.9% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 49,052 psi | 77% | 2953 fps | 95.8% |
| ReloadSwiss RS 52 | 36.4 gr | 80% | 38,145 psi | 60% | 2841 fps | 95.9% |
| ReloadSwiss RS 60 | 37 gr | 80% | 31,531 psi | 49% | 2687 fps | 96.9% |
| ReloadSwiss RS 62 | <<locked>> | 94% | 40,988 psi | 64% | 2907 fps | 95.7% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 44,715 psi | 70% | 2989 fps | 95.9% |
| Rottweil R 901 | <<locked>> | 80% | 44,077 psi | 69% | 2831 fps | 99.9% |
| Rottweil R 902 | <<locked>> | 80% | 38,290 psi | 60% | 2723 fps | 97.9% |
| Rottweil R 903 | <<locked>> | 80% | 31,662 psi | 50% | 2612 fps | 95% |
| Shooters World Long Rifle | <<locked>> | 92% | 43,468 psi | 68% | 2844 fps | 95.1% |
| Shooters World Match Rifle | <<locked>> | 80% | 39,624 psi | 62% | 2795 fps | 99.3% |
| Shooters World Precision | <<locked>> | 80% | 36,434 psi | 57% | 2700 fps | 97.4% |
| Shooters World SW4350 | <<locked>> | 98% | 49,516 psi | 78% | 2982 fps | 95.4% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 51,256 psi | 80% | 2949 fps | 99.6% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 34,896 psi | 55% | 2720 fps | 95.2% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 50,821 psi | 80% | 2933 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 41,046 psi | 64% | 2792 fps | 95.2% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 39,552 psi | 62% | 2782 fps | 96.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 41,597 psi | 65% | 2736 fps | 99.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 34,330 psi | 54% | 2589 fps | 99.5% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 49,197 psi | 77% | 2900 fps | 95.1% |
| Somchem S321 | <<locked>> | 80% | 46,282 psi | 73% | 2913 fps | 99.4% |
| Somchem S335 | <<locked>> | 80% | 41,292 psi | 65% | 2740 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 40,698 psi | 64% | 2795 fps | 97.2% |
| Somchem S355 | <<locked>> | 80% | 32,677 psi | 51% | 2625 fps | 95.2% |
| Somchem S365 | <<locked>> | 88% | 30,501 psi | 48% | 2657 fps | 95.6% |
| Vihtavuori N130 | <<locked>> | 80% | 47,050 psi | 74% | 2812 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 41,785 psi | 65% | 2736 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 37,231 psi | 58% | 2713 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 38,247 psi | 60% | 2720 fps | 99.7% |
| Vihtavuori N150 | <<locked>> | 80% | 31,038 psi | 49% | 2562 fps | 96.2% |
| Vihtavuori N160 | <<locked>> | 92% | 40,553 psi | 64% | 2831 fps | 95.7% |
| Vihtavuori N530 | <<locked>> | 80% | 42,888 psi | 67% | 2825 fps | 98.8% |
| Vihtavuori N540 | <<locked>> | 80% | 36,695 psi | 57% | 2700 fps | 99.2% |
| Vihtavuori N550 | <<locked>> | 92% | 39,885 psi | 63% | 2831 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 33,852 psi | 53% | 2641 fps | 95.6% |
| Winchester 748 | <<locked>> | 80% | 42,279 psi | 66% | 2871 fps | 99.3% |
| Winchester 760 | <<locked>> | 98% | 51,010 psi | 80% | 3074 fps | 95.7% |
| Winchester StaBALL Match | <<locked>> | 80% | 38,928 psi | 61% | 2785 fps | 97.4% |
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 | 100gr | Frontier BTSP. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,251 fps; across all powders the maximum-charge window runs from 1,880 fps to 3,251 fps. Accurate 4350 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 55–90 %, leaving at least 10 % headroom. The 100.0 gr projectile in 0.257" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. Accurate 4350, Alliant Reloder-16, Hodgdon H414 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, Alliant Power Pro 2000-MR, ReloadSwiss RS 52 rank at the top here: for .25 WSSM with the .257 | 100gr | Frontier BTSP 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.