Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 100gr | Remington PSP bullet and 74 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Accurate High Country, Alliant Reloder-26 and Winchester StaBALL HD.
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: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 94% | 57,116 psi | 90% | 3353 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 53,983 psi | 85% | 3333 fps | 100% |
| Accurate High Country | <<locked>> | 90% | 54,694 psi | 86% | 3451 fps | 98.3% |
| Accurate MAGPRO | <<locked>> | 92% | 55,666 psi | 87% | 3448 fps | 97.4% |
| ADI AR 2209 | <<locked>> | 90% | 54,998 psi | 86% | 3389 fps | 99% |
| ADI AR 2213 | <<locked>> | 94% | 56,768 psi | 89% | 3458 fps | 98.5% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 51,024 psi | 80% | 3333 fps | 97.8% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 45,759 psi | 72% | 3287 fps | 99.3% |
| Alliant Power Pro Varmint | <<locked>> | 90% | 55,347 psi | 87% | 3389 fps | 99% |
| Alliant Reloder-16 | <<locked>> | 86% | 54,824 psi | 86% | 3399 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 56,144 psi | 88% | 3409 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 90% | 54,694 psi | 86% | 3376 fps | 99% |
| Alliant Reloder-22 | <<locked>> | 94% | 56,840 psi | 89% | 3455 fps | 99.3% |
| Alliant Reloder-23 | <<locked>> | 94% | 54,433 psi | 85% | 3366 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 57,725 psi | 90% | 3488 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 90% | 54,708 psi | 86% | 3451 fps | 100% |
| Bofors RP15 | <<locked>> | 96% | 55,782 psi | 87% | 3432 fps | 99.1% |
| Bofors RP30ᴾ | <<locked>> | 100% | 53,722 psi | 84% | 3415 fps | 98.5% |
| Bofors RP5 | <<locked>> | 94% | 56,840 psi | 89% | 3455 fps | 99.3% |
| Bofors RP7 | <<locked>> | 84% | 56,202 psi | 88% | 3337 fps | 99.6% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 56,463 psi | 88% | 3438 fps | 99.2% |
| Hodgdon H414 | <<locked>> | 84% | 55,695 psi | 87% | 3389 fps | 99.8% |
| Hodgdon H4350 | <<locked>> | 82% | 54,476 psi | 85% | 3340 fps | 99.1% |
| Hodgdon H4831 | <<locked>> | 92% | 56,623 psi | 89% | 3389 fps | 97.9% |
| Hodgdon H4831 SC | <<locked>> | 92% | 55,317 psi | 87% | 3366 fps | 97.6% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 55,187 psi | 86% | 3307 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 56,637 psi | 89% | 3570 fps | 99.9% |
| Hodgdon Superformance | <<locked>> | 84% | 56,434 psi | 88% | 3425 fps | 99.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,130 psi | 58% | 2182 fps | 100% |
| IMR 4350 | <<locked>> | 86% | 54,389 psi | 85% | 3310 fps | 99.5% |
| IMR 4451 Enduron | <<locked>> | 84% | 57,624 psi | 90% | 3360 fps | 99.8% |
| IMR 4831 | <<locked>> | 86% | 54,563 psi | 86% | 3327 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 57,217 psi | 90% | 3366 fps | 98.1% |
| IMR 7828 SSC | <<locked>> | 94% | 54,447 psi | 85% | 3425 fps | 98.2% |
| Lovex S065 | <<locked>> | 84% | 54,853 psi | 86% | 3301 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 56,637 psi | 89% | 3353 fps | 99.9% |
| Lovex S071 | <<locked>> | 98% | 54,447 psi | 85% | 3310 fps | 100% |
| Norma 204 | <<locked>> | 86% | 55,477 psi | 87% | 3373 fps | 98.9% |
| Norma 217ᴾ | <<locked>> | 100% | 41,350 psi | 65% | 3196 fps | 97.6% |
| Norma MRP | <<locked>> | 92% | 56,855 psi | 89% | 3478 fps | 99.9% |
| Norma URP | <<locked>> | 86% | 56,130 psi | 88% | 3373 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 55,347 psi | 87% | 3448 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 86% | 55,114 psi | 86% | 3376 fps | 100% |
| Ramshot Magnum | <<locked>> | 96% | 53,824 psi | 84% | 3369 fps | 99.5% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,797 psi | 59% | 2228 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 54,114 psi | 85% | 3353 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 56,391 psi | 88% | 3448 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 98% | 53,577 psi | 84% | 3491 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 52,736 psi | 83% | 3428 fps | 97.1% |
| Rottweil R 903 | <<locked>> | 82% | 57,522 psi | 90% | 3337 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 55,999 psi | 88% | 3353 fps | 98.3% |
| Rottweil R 905 | <<locked>> | 90% | 54,201 psi | 85% | 3366 fps | 99% |
| Rottweil R 907 | <<locked>> | 84% | 56,202 psi | 88% | 3337 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 84% | 54,853 psi | 86% | 3301 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 56,637 psi | 89% | 3353 fps | 99.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 57,203 psi | 90% | 3192 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 57,725 psi | 90% | 3304 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 57,377 psi | 90% | 3425 fps | 99.4% |
| Somchem S355 | <<locked>> | 82% | 57,188 psi | 90% | 3330 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 54,259 psi | 85% | 3278 fps | 97.4% |
| Somchem S365 | <<locked>> | 88% | 56,884 psi | 89% | 3379 fps | 100% |
| Somchem S385 | <<locked>> | 90% | 54,752 psi | 86% | 3337 fps | 99.5% |
| Vihtavuori N150 | <<locked>> | 82% | 54,795 psi | 86% | 3241 fps | 100% |
| Vihtavuori N160 | <<locked>> | 84% | 54,172 psi | 85% | 3304 fps | 100% |
| Vihtavuori N165 | <<locked>> | 94% | 54,462 psi | 85% | 3310 fps | 99.3% |
| Vihtavuori N550 | <<locked>> | 86% | 57,130 psi | 90% | 3369 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 56,492 psi | 89% | 3396 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 56,565 psi | 89% | 3471 fps | 98.1% |
| Vihtavuori N565 | <<locked>> | 98% | 56,782 psi | 89% | 3445 fps | 98.4% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 53,563 psi | 84% | 3432 fps | 96.7% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 57,740 psi | 90% | 3310 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 55,912 psi | 88% | 3392 fps | 99.8% |
| Winchester StaBALL HD | <<locked>> | 96% | 56,637 psi | 89% | 3514 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 54,549 psi | 85% | 3323 fps | 99% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 35,143 psi | 55% | 2897 fps | 96.7% |
| Accurate 4350 | <<locked>> | 80% | 46,963 psi | 74% | 3202 fps | 99.9% |
| Accurate High Country | 63.4 gr | 84% | 44,164 psi | 69% | 3228 fps | 95.7% |
| Accurate MAGPRO | <<locked>> | 88% | 48,167 psi | 75% | 3297 fps | 95.5% |
| ADI AR 2209 | <<locked>> | 80% | 39,088 psi | 61% | 3045 fps | 95.1% |
| ADI AR 2213 | <<locked>> | 86% | 42,888 psi | 67% | 3166 fps | 95% |
| ADI AR 2217 | <<locked>> | 96% | 44,411 psi | 70% | 3189 fps | 96% |
| ADI AR 2225 | <<locked>> | 92% | 35,041 psi | 55% | 2999 fps | 95.7% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 39,494 psi | 62% | 3048 fps | 95.3% |
| Alliant Reloder-16 | <<locked>> | 80% | 44,831 psi | 70% | 3209 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 52,286 psi | 82% | 3346 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 39,131 psi | 61% | 3038 fps | 95.2% |
| Alliant Reloder-22 | <<locked>> | 84% | 40,350 psi | 63% | 3107 fps | 95.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 33,736 psi | 53% | 2933 fps | 99.2% |
| Alliant Reloder-25 | <<locked>> | 82% | 31,459 psi | 49% | 2884 fps | 95.8% |
| Alliant Reloder-26 | 62.2 gr | 80% | 37,275 psi | 58% | 3087 fps | 98.7% |
| Bofors RP15 | <<locked>> | 86% | 40,001 psi | 63% | 3094 fps | 95.5% |
| Bofors RP30 | <<locked>> | 92% | 40,567 psi | 64% | 3136 fps | 95.1% |
| Bofors RP5 | <<locked>> | 84% | 40,350 psi | 63% | 3107 fps | 95.8% |
| Bofors RP7 | <<locked>> | 80% | 49,559 psi | 78% | 3209 fps | 98.8% |
| Hodgdon H1000 | <<locked>> | 92% | 42,699 psi | 67% | 3153 fps | 96.1% |
| Hodgdon H414 | <<locked>> | 80% | 48,559 psi | 76% | 3251 fps | 99% |
| Hodgdon H4350 | <<locked>> | 80% | 51,155 psi | 80% | 3278 fps | 98.6% |
| Hodgdon H4831 | <<locked>> | 86% | 45,847 psi | 72% | 3176 fps | 95.3% |
| Hodgdon H4831 SC | <<locked>> | 86% | 44,976 psi | 70% | 3156 fps | 95.1% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 42,279 psi | 66% | 3071 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 37,550 psi | 59% | 3120 fps | 95.3% |
| Hodgdon Superformance | <<locked>> | 80% | 48,559 psi | 76% | 3278 fps | 98.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,746 psi | 43% | 1955 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 44,875 psi | 70% | 3123 fps | 98% |
| IMR 4451 Enduron | <<locked>> | 80% | 50,705 psi | 79% | 3235 fps | 99.2% |
| IMR 4831 | <<locked>> | 80% | 44,773 psi | 70% | 3140 fps | 99.8% |
| IMR 4955 Enduron | <<locked>> | 84% | 44,454 psi | 70% | 3110 fps | 95.1% |
| IMR 7828 SSC | <<locked>> | 88% | 44,338 psi | 69% | 3215 fps | 95.7% |
| Lovex S065 | <<locked>> | 80% | 48,443 psi | 76% | 3179 fps | 99.6% |
| Lovex S070 | <<locked>> | 80% | 46,746 psi | 73% | 3163 fps | 98.9% |
| Lovex S071 | <<locked>> | 82% | 32,372 psi | 51% | 2818 fps | 95.5% |
| Norma 204 | <<locked>> | 80% | 45,034 psi | 71% | 3163 fps | 96.9% |
| Norma 217 | <<locked>> | 96% | 35,897 psi | 56% | 3051 fps | 95.5% |
| Norma MRP | <<locked>> | 80% | 36,695 psi | 57% | 3041 fps | 96% |
| Norma URP | <<locked>> | 80% | 46,006 psi | 72% | 3186 fps | 99.9% |
| Ramshot Grand | <<locked>> | 88% | 44,237 psi | 69% | 3222 fps | 96.1% |
| Ramshot Hunter | <<locked>> | 80% | 44,904 psi | 70% | 3176 fps | 99% |
| Ramshot Magnum | <<locked>> | 86% | 36,869 psi | 58% | 3005 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,413 psi | 45% | 2005 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 47,094 psi | 74% | 3222 fps | 99.9% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 45,295 psi | 71% | 3238 fps | 99.8% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 34,403 psi | 54% | 3012 fps | 95.2% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 48,675 psi | 76% | 3343 fps | 96% |
| Rottweil R 903 | <<locked>> | 80% | 53,969 psi | 85% | 3278 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 43,134 psi | 68% | 3091 fps | 95.3% |
| Rottweil R 905 | <<locked>> | 80% | 38,522 psi | 60% | 3025 fps | 95.2% |
| Rottweil R 907 | <<locked>> | 80% | 49,559 psi | 78% | 3209 fps | 98.8% |
| Shooters World Long Rifle | <<locked>> | 80% | 48,443 psi | 76% | 3179 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 80% | 46,746 psi | 73% | 3163 fps | 98.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 53,679 psi | 84% | 3143 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 47,514 psi | 74% | 3120 fps | 98.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 38,189 psi | 60% | 3018 fps | 95% |
| Somchem S355 | <<locked>> | 80% | 53,693 psi | 84% | 3274 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 47,384 psi | 74% | 3146 fps | 95.8% |
| Somchem S365 | <<locked>> | 80% | 43,047 psi | 67% | 3136 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 39,218 psi | 61% | 3009 fps | 96.4% |
| Vihtavuori N150 | <<locked>> | 80% | 51,387 psi | 81% | 3182 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 47,369 psi | 74% | 3179 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 82% | 36,318 psi | 57% | 2923 fps | 95% |
| Vihtavuori N550 | <<locked>> | 80% | 46,920 psi | 74% | 3182 fps | 99.9% |
| Vihtavuori N555 | <<locked>> | 80% | 37,840 psi | 59% | 3022 fps | 99.2% |
| Vihtavuori N560 | <<locked>> | 86% | 45,788 psi | 72% | 3251 fps | 95.5% |
| Vihtavuori N565 | <<locked>> | 92% | 46,006 psi | 72% | 3232 fps | 96% |
| Vihtavuori N568 | <<locked>> | 98% | 49,821 psi | 78% | 3356 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 46,702 psi | 73% | 3130 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 48,762 psi | 76% | 3258 fps | 99.1% |
| Winchester StaBALL HD | 59.7 gr | 80% | 30,037 psi | 47% | 2940 fps | 99.3% |
| Winchester Supreme 780 | <<locked>> | 82% | 38,334 psi | 60% | 2982 fps | 95% |
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 74 powders for .257 Weath. Mag. loaded with the .257 | 100gr | Remington PSP. Hodgdon Retumbo delivers the highest muzzle velocity at 3,570 fps; across all powders the maximum-charge window runs from 2,182 fps to 3,570 fps. ADI AR 2217 gives the best case fill at 100 %, and 74 of the 74 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 100.0 gr projectile in 0.257" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-25 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. Accurate High Country, Alliant Reloder-26, Winchester StaBALL HD rank at the top here: for .257 Weath. Mag. with the .257 | 100gr | Remington PSP 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.