Load Specifications
Bullet Manufacturer:Impala 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:1:10.0
Load data in caliber .25 WSSM with .257 | 100gr | Impala RNFP KO 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 Power Pro 2000-MR, ReloadSwiss RS 60 and Alliant Reloder-17.
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.
A valid access license is required to use the Personalized Load Calculator.
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% | 55,143 psi | 86% | 2959 fps | 100% |
| Accurate 2460 | <<locked>> | 82% | 56,855 psi | 89% | 3031 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 54,418 psi | 85% | 2989 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 55,027 psi | 86% | 3041 fps | 100% |
| Accurate 4064 | <<locked>> | 92% | 57,609 psi | 90% | 3084 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 56,507 psi | 89% | 3150 fps | 99.1% |
| ADI AR 2206H | <<locked>> | 88% | 57,029 psi | 89% | 3100 fps | 99.7% |
| ADI AR 2208 | <<locked>> | 94% | 57,493 psi | 90% | 3091 fps | 99.5% |
| ADI Benchmark 8208 | <<locked>> | 86% | 55,941 psi | 88% | 3051 fps | 100% |
| Alliant AR-Comp | <<locked>> | 86% | 56,463 psi | 88% | 3031 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 90% | 56,159 psi | 88% | 3215 fps | 99.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 54,404 psi | 85% | 3071 fps | 99.9% |
| Alliant Reloder-10x | <<locked>> | 82% | 57,479 psi | 90% | 3005 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 90% | 55,143 psi | 86% | 3091 fps | 99.3% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 53,650 psi | 84% | 3143 fps | 99% |
| Alliant Reloder-17 | <<locked>> | 96% | 54,853 psi | 86% | 3189 fps | 99.9% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 39,175 psi | 61% | 2864 fps | 97.3% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 43,352 psi | 68% | 3015 fps | 96.1% |
| Baschieri & Pellagri 107 | <<locked>> | 88% | 56,594 psi | 89% | 3110 fps | 99.2% |
| Bofors RP3 | <<locked>> | 92% | 55,317 psi | 87% | 3091 fps | 99.9% |
| Bofors RP7 | <<locked>> | 96% | 55,463 psi | 87% | 3041 fps | 95.9% |
| Hodgdon Benchmark | <<locked>> | 86% | 57,638 psi | 90% | 3031 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 55,448 psi | 87% | 3084 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 84% | 56,985 psi | 89% | 3182 fps | 99.5% |
| Hodgdon H322 | <<locked>> | 82% | 56,507 psi | 89% | 3051 fps | 100% |
| Hodgdon H335 | <<locked>> | 82% | 57,580 psi | 90% | 3074 fps | 100% |
| Hodgdon H380 | <<locked>> | 92% | 56,347 psi | 88% | 3097 fps | 98.7% |
| Hodgdon H414 | <<locked>> | 98% | 55,027 psi | 86% | 3133 fps | 96.6% |
| Hodgdon H4895 | <<locked>> | 88% | 57,537 psi | 90% | 3114 fps | 99.9% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 49,951 psi | 78% | 3015 fps | 99.4% |
| Hodgdon LEVERevolution | <<locked>> | 90% | 56,637 psi | 89% | 3146 fps | 100% |
| Hodgdon Superformance | <<locked>> | 98% | 55,927 psi | 88% | 3163 fps | 96.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,752 psi | 56% | 1893 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 55,230 psi | 87% | 3061 fps | 99.8% |
| IMR 3031 | <<locked>> | 88% | 57,450 psi | 90% | 3100 fps | 100% |
| IMR 4064 | <<locked>> | 92% | 57,406 psi | 90% | 3081 fps | 99.6% |
| IMR 4166 Enduron | <<locked>> | 90% | 57,493 psi | 90% | 3051 fps | 96.9% |
| IMR 4198 | <<locked>> | 82% | 56,797 psi | 89% | 2959 fps | 100% |
| IMR 4350ᴾ | <<locked>> | 100% | 54,940 psi | 86% | 3058 fps | 95.9% |
| IMR 4451 Enduron | <<locked>> | 96% | 57,058 psi | 89% | 3074 fps | 96.7% |
| IMR 4831ᴾ | <<locked>> | 100% | 53,171 psi | 83% | 3081 fps | 98.7% |
| IMR 4895 | <<locked>> | 90% | 56,507 psi | 89% | 3127 fps | 99.7% |
| IMR 8208 XBR | <<locked>> | 86% | 55,941 psi | 88% | 3051 fps | 100% |
| Lovex D073.5 | <<locked>> | 82% | 56,942 psi | 89% | 3045 fps | 100% |
| Lovex D073.6 | <<locked>> | 88% | 57,174 psi | 90% | 3084 fps | 100% |
| Lovex S060 | <<locked>> | 88% | 56,318 psi | 88% | 3022 fps | 99.7% |
| Lovex S062 | <<locked>> | 92% | 57,595 psi | 90% | 3084 fps | 100% |
| Lovex S065 | <<locked>> | 98% | 56,579 psi | 89% | 3071 fps | 98% |
| Lovex S070ᴾ | <<locked>> | 100% | 57,551 psi | 90% | 3104 fps | 97.2% |
| Norma 201 | <<locked>> | 88% | 56,086 psi | 88% | 3048 fps | 100% |
| Norma 202 | <<locked>> | 88% | 56,115 psi | 88% | 3048 fps | 100% |
| Norma 203B | <<locked>> | 90% | 54,433 psi | 85% | 3081 fps | 99.6% |
| Norma URPᴾ | <<locked>> | 100% | 54,940 psi | 86% | 3130 fps | 98.9% |
| Ramshot Big Game | <<locked>> | 90% | 54,389 psi | 85% | 3097 fps | 99.5% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 53,679 psi | 84% | 3114 fps | 97.2% |
| Ramshot TAC | <<locked>> | 86% | 56,304 psi | 88% | 3061 fps | 98.1% |
| Ramshot Wild Boar | <<locked>> | 86% | 55,695 psi | 87% | 3084 fps | 99.6% |
| Ramshot X-Terminator | <<locked>> | 84% | 56,811 psi | 89% | 3048 fps | 99.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,303 psi | 57% | 1939 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 55,303 psi | 87% | 3031 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 92% | 56,260 psi | 88% | 3068 fps | 97.3% |
| ReloadSwiss RS 52 | <<locked>> | 88% | 55,259 psi | 87% | 3159 fps | 99.3% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 54,433 psi | 85% | 3189 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 55,477 psi | 87% | 3163 fps | 98.8% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 55,448 psi | 87% | 3186 fps | 98.5% |
| Rottweil R 901 | <<locked>> | 84% | 54,476 psi | 85% | 2992 fps | 100% |
| Rottweil R 902 | <<locked>> | 90% | 56,507 psi | 89% | 3045 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 55,187 psi | 86% | 3077 fps | 99.8% |
| Rottweil R 907 | <<locked>> | 96% | 55,463 psi | 87% | 3041 fps | 95.9% |
| Shooters World Long Rifle | <<locked>> | 98% | 56,579 psi | 89% | 3071 fps | 98% |
| Shooters World Match Rifle | <<locked>> | 88% | 57,174 psi | 90% | 3084 fps | 100% |
| Shooters World Precision | <<locked>> | 92% | 57,595 psi | 90% | 3084 fps | 100% |
| Shooters World SW4350ᴾ | <<locked>> | 100% | 57,551 psi | 90% | 3104 fps | 97.2% |
| SNPE Vectan SP 11 | <<locked>> | 94% | 56,101 psi | 88% | 3130 fps | 99.7% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 54,998 psi | 86% | 3041 fps | 98.4% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 55,361 psi | 87% | 3068 fps | 99.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 88% | 57,116 psi | 90% | 2982 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 94% | 57,305 psi | 90% | 2979 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 98% | 57,188 psi | 90% | 3022 fps | 96.8% |
| Somchem S321 | <<locked>> | 84% | 57,638 psi | 90% | 3091 fps | 100% |
| Somchem S335 | <<locked>> | 88% | 56,739 psi | 89% | 2982 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 54,099 psi | 85% | 3031 fps | 99.4% |
| Somchem S355 | <<locked>> | 94% | 55,550 psi | 87% | 3077 fps | 99.8% |
| Somchem S365ᴾ | <<locked>> | 100% | 49,414 psi | 77% | 3077 fps | 99.9% |
| Vihtavuori N130 | <<locked>> | 84% | 57,261 psi | 90% | 2953 fps | 100% |
| Vihtavuori N133 | <<locked>> | 88% | 57,116 psi | 90% | 2966 fps | 100% |
| Vihtavuori N135 | <<locked>> | 90% | 55,999 psi | 88% | 3015 fps | 100% |
| Vihtavuori N140 | <<locked>> | 90% | 56,492 psi | 89% | 3025 fps | 100% |
| Vihtavuori N150 | <<locked>> | 96% | 56,681 psi | 89% | 3051 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 57,624 psi | 90% | 3127 fps | 99.1% |
| Vihtavuori N530 | <<locked>> | 86% | 56,420 psi | 88% | 3051 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 55,201 psi | 87% | 3025 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 56,536 psi | 89% | 3130 fps | 98.9% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 42,496 psi | 67% | 2949 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 54,360 psi | 85% | 3048 fps | 99.8% |
| Winchester 748 | <<locked>> | 86% | 56,246 psi | 88% | 3100 fps | 100% |
| Winchester 760 | <<locked>> | 98% | 55,405 psi | 87% | 3140 fps | 96.7% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 35,360 psi | 55% | 2844 fps | 96.5% |
| Winchester StaBALL Match | <<locked>> | 88% | 55,027 psi | 86% | 3074 fps | 99.8% |
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% | 48,762 psi | 76% | 2861 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 53,534 psi | 84% | 2979 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 42,685 psi | 67% | 2795 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 48,298 psi | 76% | 2933 fps | 100% |
| Accurate 4064 | <<locked>> | 80% | 40,277 psi | 63% | 2785 fps | 99.9% |
| Accurate 4350 | <<locked>> | 88% | 38,116 psi | 60% | 2802 fps | 95.2% |
| ADI AR 2206H | <<locked>> | 80% | 44,846 psi | 70% | 2881 fps | 98.2% |
| ADI AR 2208 | <<locked>> | 80% | 38,363 psi | 60% | 2723 fps | 95.9% |
| ADI Benchmark 8208 | <<locked>> | 80% | 46,673 psi | 73% | 2890 fps | 99.4% |
| Alliant AR-Comp | <<locked>> | 80% | 46,746 psi | 73% | 2887 fps | 100% |
| Alliant Power Pro 2000-MR | 38.1 gr | 80% | 40,509 psi | 63% | 2894 fps | 96.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 38,058 psi | 60% | 2749 fps | 97.5% |
| Alliant Reloder-10x | <<locked>> | 80% | 54,404 psi | 85% | 2963 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 40,727 psi | 64% | 2812 fps | 96.8% |
| Alliant Reloder-16 | <<locked>> | 88% | 37,855 psi | 59% | 2802 fps | 95% |
| Alliant Reloder-17 | 37.6 gr | 80% | 33,185 psi | 52% | 2703 fps | 95% |
| Alliant Reloder-23 | <<locked>> | 96% | 34,882 psi | 55% | 2749 fps | 95.7% |
| Alliant Reloder-26 | <<locked>> | 98% | 40,509 psi | 63% | 2946 fps | 95% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 43,714 psi | 69% | 2874 fps | 97% |
| Bofors RP3 | <<locked>> | 80% | 38,101 psi | 60% | 2759 fps | 97.7% |
| Bofors RP7 | <<locked>> | 94% | 52,185 psi | 82% | 2986 fps | 95.2% |
| Hodgdon Benchmark | <<locked>> | 80% | 48,559 psi | 76% | 2884 fps | 99.8% |
| Hodgdon BL-C2 | <<locked>> | 80% | 45,585 psi | 71% | 2913 fps | 99.6% |
| Hodgdon CFE223 | <<locked>> | 80% | 49,574 psi | 78% | 3058 fps | 98.7% |
| Hodgdon H322 | <<locked>> | 80% | 53,084 psi | 83% | 2999 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 54,201 psi | 85% | 3025 fps | 100% |
| Hodgdon H380 | <<locked>> | 82% | 41,147 psi | 64% | 2808 fps | 95.5% |
| Hodgdon H414 | <<locked>> | 94% | 48,660 psi | 76% | 3018 fps | 95.1% |
| Hodgdon H4895 | <<locked>> | 80% | 45,237 psi | 71% | 2897 fps | 98.8% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 32,895 psi | 52% | 2638 fps | 95.1% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 41,031 psi | 64% | 2861 fps | 98.4% |
| Hodgdon Superformance | <<locked>> | 96% | 52,214 psi | 82% | 3097 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,832 psi | 42% | 1696 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 43,250 psi | 68% | 2841 fps | 98.3% |
| IMR 3031 | <<locked>> | 80% | 44,686 psi | 70% | 2897 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 40,277 psi | 63% | 2759 fps | 96.7% |
| IMR 4166 Enduron | <<locked>> | 86% | 51,039 psi | 80% | 2943 fps | 95.6% |
| IMR 4198 | <<locked>> | 80% | 53,679 psi | 84% | 2913 fps | 100% |
| IMR 4350 | <<locked>> | 98% | 51,779 psi | 81% | 3005 fps | 95.1% |
| IMR 4451 Enduron | <<locked>> | 92% | 50,604 psi | 79% | 2963 fps | 95.4% |
| IMR 4831 | <<locked>> | 90% | 38,899 psi | 61% | 2802 fps | 95.6% |
| IMR 4895 | <<locked>> | 80% | 41,669 psi | 65% | 2848 fps | 97.7% |
| IMR 8208 XBR | <<locked>> | 80% | 46,673 psi | 73% | 2890 fps | 99.4% |
| Lovex D073.5 | <<locked>> | 80% | 53,287 psi | 84% | 2986 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 44,280 psi | 69% | 2871 fps | 99.8% |
| Lovex S060 | <<locked>> | 80% | 44,672 psi | 70% | 2812 fps | 98.2% |
| Lovex S062 | <<locked>> | 80% | 40,321 psi | 63% | 2769 fps | 98.4% |
| Lovex S065 | <<locked>> | 90% | 44,817 psi | 70% | 2858 fps | 95.6% |
| Lovex S070 | <<locked>> | 94% | 48,080 psi | 75% | 2940 fps | 95.2% |
| Norma 201 | <<locked>> | 80% | 44,338 psi | 69% | 2838 fps | 99.1% |
| Norma 202 | <<locked>> | 80% | 44,251 psi | 69% | 2848 fps | 100% |
| Norma 203B | <<locked>> | 80% | 40,132 psi | 63% | 2802 fps | 97.2% |
| Norma URP | <<locked>> | 88% | 38,087 psi | 60% | 2795 fps | 95% |
| Ramshot Big Game | <<locked>> | 80% | 39,320 psi | 62% | 2805 fps | 96.8% |
| Ramshot Hunter | <<locked>> | 96% | 47,514 psi | 74% | 3002 fps | 95.8% |
| Ramshot TAC | <<locked>> | 80% | 46,659 psi | 73% | 2887 fps | 96.3% |
| Ramshot Wild Boar | <<locked>> | 80% | 46,224 psi | 72% | 2917 fps | 98.5% |
| Ramshot X-Terminator | <<locked>> | 80% | 50,198 psi | 79% | 2936 fps | 99% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,122 psi | 43% | 1736 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 52,040 psi | 82% | 2979 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 46,731 psi | 73% | 2897 fps | 95.2% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 42,351 psi | 66% | 2917 fps | 97.2% |
| ReloadSwiss RS 60 | 37.6 gr | 80% | 35,128 psi | 55% | 2779 fps | 98.4% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 40,001 psi | 63% | 2867 fps | 95.4% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 42,859 psi | 67% | 2933 fps | 95.3% |
| Rottweil R 901 | <<locked>> | 80% | 48,689 psi | 76% | 2894 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 42,366 psi | 66% | 2789 fps | 98.8% |
| Rottweil R 903 | <<locked>> | 80% | 35,955 psi | 56% | 2700 fps | 96.7% |
| Rottweil R 907 | <<locked>> | 94% | 52,185 psi | 82% | 2986 fps | 95.2% |
| Shooters World Long Rifle | <<locked>> | 90% | 44,817 psi | 70% | 2858 fps | 95.6% |
| Shooters World Match Rifle | <<locked>> | 80% | 44,280 psi | 69% | 2871 fps | 99.8% |
| Shooters World Precision | <<locked>> | 80% | 40,321 psi | 63% | 2769 fps | 98.4% |
| Shooters World SW4350 | <<locked>> | 94% | 48,080 psi | 75% | 2940 fps | 95.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 36,390 psi | 57% | 2740 fps | 95.9% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 45,223 psi | 71% | 2864 fps | 96.5% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 43,323 psi | 68% | 2848 fps | 97.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 45,498 psi | 71% | 2795 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 37,985 psi | 60% | 2651 fps | 99.9% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 50,488 psi | 79% | 2910 fps | 95.5% |
| Somchem S321 | <<locked>> | 80% | 50,415 psi | 79% | 2976 fps | 99.8% |
| Somchem S335 | <<locked>> | 80% | 45,063 psi | 71% | 2792 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 44,512 psi | 70% | 2858 fps | 98.1% |
| Somchem S355 | <<locked>> | 80% | 36,608 psi | 57% | 2703 fps | 96.7% |
| Somchem S365 | <<locked>> | 84% | 30,516 psi | 48% | 2635 fps | 95.7% |
| Vihtavuori N130 | <<locked>> | 80% | 51,039 psi | 80% | 2861 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 45,542 psi | 71% | 2785 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 41,626 psi | 65% | 2779 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 41,901 psi | 66% | 2779 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 80% | 34,766 psi | 54% | 2635 fps | 97.5% |
| Vihtavuori N160 | <<locked>> | 88% | 39,595 psi | 62% | 2795 fps | 95.4% |
| Vihtavuori N530 | <<locked>> | 80% | 46,862 psi | 73% | 2887 fps | 99.4% |
| Vihtavuori N540 | <<locked>> | 80% | 40,640 psi | 64% | 2769 fps | 99.7% |
| Vihtavuori N550 | <<locked>> | 88% | 38,972 psi | 61% | 2795 fps | 95% |
| Vihtavuori N555 | <<locked>> | 96% | 37,521 psi | 59% | 2838 fps | 95.8% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 32,996 psi | 52% | 2602 fps | 95.3% |
| Winchester 748 | <<locked>> | 80% | 46,340 psi | 73% | 2936 fps | 99.8% |
| Winchester 760 | <<locked>> | 94% | 48,660 psi | 76% | 3018 fps | 95.1% |
| Winchester StaBALL HD | <<locked>> | 98% | 33,417 psi | 52% | 2779 fps | 95.3% |
| Winchester StaBALL Match | <<locked>> | 80% | 42,569 psi | 67% | 2848 fps | 98.3% |
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 | Impala RNFP KO. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,215 fps; across all powders the maximum-charge window runs from 1,893 fps to 3,215 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 1:10.0 twist; slower twists will usually not stabilise this weight. Accurate 4350, 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 Power Pro 2000-MR, ReloadSwiss RS 60, Alliant Reloder-17 rank at the top here: for .25 WSSM with the .257 | 100gr | Impala RNFP KO 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.