Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 100gr | Nosler Ballistic Tip Hunting bullet and 74 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-25, Winchester StaBALL HD and Accurate High Country.
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% | 56,797 psi | 89% | 3350 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 57,667 psi | 90% | 3392 fps | 100% |
| Accurate High Country | <<locked>> | 90% | 54,360 psi | 85% | 3442 fps | 98.2% |
| Accurate MAGPRO | <<locked>> | 92% | 55,405 psi | 87% | 3445 fps | 97.3% |
| ADI AR 2209 | <<locked>> | 90% | 54,955 psi | 86% | 3389 fps | 99% |
| ADI AR 2213 | <<locked>> | 94% | 56,463 psi | 88% | 3455 fps | 98.4% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 50,807 psi | 80% | 3330 fps | 97.8% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 45,556 psi | 71% | 3281 fps | 99.2% |
| Alliant Power Pro Varmint | <<locked>> | 90% | 55,100 psi | 86% | 3386 fps | 99% |
| Alliant Reloder-16 | <<locked>> | 86% | 54,752 psi | 86% | 3396 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 55,811 psi | 87% | 3409 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 90% | 54,447 psi | 85% | 3373 fps | 98.9% |
| Alliant Reloder-22 | <<locked>> | 94% | 56,565 psi | 89% | 3445 fps | 99.3% |
| Alliant Reloder-23 | <<locked>> | 94% | 54,128 psi | 85% | 3360 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 57,479 psi | 90% | 3484 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 90% | 54,708 psi | 86% | 3455 fps | 100% |
| Bofors RP15 | <<locked>> | 96% | 55,724 psi | 87% | 3432 fps | 99.1% |
| Bofors RP30ᴾ | <<locked>> | 100% | 53,417 psi | 84% | 3412 fps | 98.4% |
| Bofors RP5 | <<locked>> | 94% | 56,565 psi | 89% | 3445 fps | 99.3% |
| Bofors RP7 | <<locked>> | 84% | 56,159 psi | 88% | 3333 fps | 99.6% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 56,173 psi | 88% | 3435 fps | 99.2% |
| Hodgdon H414 | <<locked>> | 84% | 55,637 psi | 87% | 3389 fps | 99.8% |
| Hodgdon H4350 | <<locked>> | 82% | 54,462 psi | 85% | 3340 fps | 99.1% |
| Hodgdon H4831 | <<locked>> | 92% | 56,318 psi | 88% | 3383 fps | 97.8% |
| Hodgdon H4831 SC | <<locked>> | 92% | 55,288 psi | 87% | 3366 fps | 97.6% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 55,129 psi | 86% | 3307 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 56,333 psi | 88% | 3563 fps | 99.9% |
| Hodgdon Superformance | <<locked>> | 84% | 56,391 psi | 88% | 3425 fps | 99.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,028 psi | 58% | 2178 fps | 100% |
| IMR 4350 | <<locked>> | 86% | 54,331 psi | 85% | 3310 fps | 99.5% |
| IMR 4451 Enduron | <<locked>> | 84% | 57,566 psi | 90% | 3360 fps | 99.8% |
| IMR 4831 | <<locked>> | 86% | 54,273 psi | 85% | 3320 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 57,217 psi | 90% | 3366 fps | 98.1% |
| IMR 7828 SSC | <<locked>> | 94% | 54,447 psi | 85% | 3428 fps | 98.2% |
| Lovex S065 | <<locked>> | 84% | 54,824 psi | 86% | 3301 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 56,594 psi | 89% | 3353 fps | 99.9% |
| Lovex S071 | <<locked>> | 98% | 54,172 psi | 85% | 3304 fps | 99.9% |
| Norma 204 | <<locked>> | 86% | 55,448 psi | 87% | 3373 fps | 98.9% |
| Norma 217ᴾ | <<locked>> | 100% | 41,118 psi | 64% | 3192 fps | 97.5% |
| Norma MRP | <<locked>> | 92% | 56,521 psi | 89% | 3471 fps | 99.9% |
| Norma URP | <<locked>> | 86% | 56,072 psi | 88% | 3373 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 55,317 psi | 87% | 3451 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 86% | 55,071 psi | 86% | 3376 fps | 100% |
| Ramshot Magnum | <<locked>> | 96% | 53,853 psi | 84% | 3373 fps | 99.5% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,898 psi | 59% | 2231 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 54,070 psi | 85% | 3353 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 56,347 psi | 88% | 3448 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 57,696 psi | 90% | 3563 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 52,489 psi | 82% | 3422 fps | 97% |
| Rottweil R 903 | <<locked>> | 82% | 57,479 psi | 90% | 3337 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 55,970 psi | 88% | 3353 fps | 98.3% |
| Rottweil R 905 | <<locked>> | 90% | 53,882 psi | 84% | 3360 fps | 98.9% |
| Rottweil R 907 | <<locked>> | 84% | 56,159 psi | 88% | 3333 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 84% | 54,824 psi | 86% | 3301 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 56,594 psi | 89% | 3353 fps | 99.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 56,898 psi | 89% | 3192 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 57,682 psi | 90% | 3304 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 57,377 psi | 90% | 3422 fps | 99.3% |
| Somchem S355 | <<locked>> | 82% | 57,116 psi | 90% | 3330 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 53,998 psi | 85% | 3274 fps | 97.4% |
| Somchem S365 | <<locked>> | 88% | 56,579 psi | 89% | 3373 fps | 100% |
| Somchem S385 | <<locked>> | 90% | 54,447 psi | 85% | 3330 fps | 99.5% |
| Vihtavuori N150 | <<locked>> | 82% | 54,737 psi | 86% | 3238 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 57,696 psi | 90% | 3363 fps | 100% |
| Vihtavuori N165 | <<locked>> | 94% | 54,172 psi | 85% | 3307 fps | 99.3% |
| Vihtavuori N550 | <<locked>> | 86% | 57,101 psi | 89% | 3369 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 56,449 psi | 88% | 3396 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 56,260 psi | 88% | 3465 fps | 98.1% |
| Vihtavuori N565 | <<locked>> | 98% | 56,507 psi | 89% | 3442 fps | 98.3% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 53,606 psi | 84% | 3432 fps | 96.7% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 57,740 psi | 90% | 3310 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 55,637 psi | 87% | 3389 fps | 99.8% |
| Winchester StaBALL HD | <<locked>> | 96% | 56,318 psi | 88% | 3510 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 54,534 psi | 85% | 3323 fps | 98.9% |
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% | 35,056 psi | 55% | 2897 fps | 96.6% |
| Accurate 4350 | <<locked>> | 80% | 46,891 psi | 73% | 3202 fps | 99.9% |
| Accurate High Country | 63.2 gr | 84% | 43,918 psi | 69% | 3225 fps | 95.7% |
| Accurate MAGPRO | <<locked>> | 88% | 48,109 psi | 75% | 3297 fps | 95.5% |
| ADI AR 2209 | <<locked>> | 80% | 39,073 psi | 61% | 3045 fps | 95.1% |
| ADI AR 2213 | <<locked>> | 86% | 42,844 psi | 67% | 3166 fps | 95% |
| ADI AR 2217 | <<locked>> | 96% | 44,396 psi | 70% | 3189 fps | 96% |
| ADI AR 2225 | <<locked>> | 92% | 34,867 psi | 55% | 2992 fps | 95.6% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 39,436 psi | 62% | 3045 fps | 95.3% |
| Alliant Reloder-16 | <<locked>> | 80% | 44,773 psi | 70% | 3209 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 51,996 psi | 81% | 3343 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 39,073 psi | 61% | 3038 fps | 95.2% |
| Alliant Reloder-22 | <<locked>> | 84% | 40,103 psi | 63% | 3104 fps | 95.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 33,678 psi | 53% | 2930 fps | 99.2% |
| Alliant Reloder-25 | 58.8 gr | 82% | 31,256 psi | 49% | 2877 fps | 95.7% |
| Alliant Reloder-26 | <<locked>> | 80% | 37,028 psi | 58% | 3081 fps | 98.6% |
| Bofors RP15 | <<locked>> | 86% | 39,972 psi | 63% | 3097 fps | 95.5% |
| Bofors RP30 | <<locked>> | 92% | 40,509 psi | 63% | 3133 fps | 95% |
| Bofors RP5 | <<locked>> | 84% | 40,103 psi | 63% | 3104 fps | 95.7% |
| Bofors RP7 | <<locked>> | 80% | 49,284 psi | 77% | 3205 fps | 98.8% |
| Hodgdon H1000 | <<locked>> | 92% | 42,438 psi | 67% | 3146 fps | 96% |
| Hodgdon H414 | <<locked>> | 80% | 48,486 psi | 76% | 3251 fps | 99% |
| Hodgdon H4350 | <<locked>> | 80% | 50,879 psi | 80% | 3271 fps | 98.5% |
| Hodgdon H4831 | <<locked>> | 86% | 45,803 psi | 72% | 3176 fps | 95.3% |
| Hodgdon H4831 SC | <<locked>> | 86% | 44,962 psi | 70% | 3156 fps | 95% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 42,221 psi | 66% | 3071 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 37,347 psi | 59% | 3114 fps | 95.2% |
| Hodgdon Superformance | <<locked>> | 80% | 48,530 psi | 76% | 3281 fps | 98.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,644 psi | 43% | 1952 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 44,831 psi | 70% | 3123 fps | 98% |
| IMR 4451 Enduron | <<locked>> | 80% | 50,662 psi | 79% | 3232 fps | 99.2% |
| IMR 4831 | <<locked>> | 80% | 44,498 psi | 70% | 3136 fps | 99.8% |
| IMR 4955 Enduron | <<locked>> | 84% | 44,396 psi | 70% | 3110 fps | 95.1% |
| IMR 7828 SSC | <<locked>> | 88% | 44,280 psi | 69% | 3212 fps | 95.6% |
| Lovex S065 | <<locked>> | 80% | 48,399 psi | 76% | 3179 fps | 99.6% |
| Lovex S070 | <<locked>> | 80% | 46,717 psi | 73% | 3163 fps | 98.9% |
| Lovex S071 | <<locked>> | 82% | 32,140 psi | 50% | 2812 fps | 95.4% |
| Norma 204 | <<locked>> | 80% | 45,005 psi | 71% | 3163 fps | 96.9% |
| Norma 217 | <<locked>> | 96% | 35,853 psi | 56% | 3048 fps | 95.4% |
| Norma MRP | <<locked>> | 80% | 36,622 psi | 57% | 3041 fps | 95.9% |
| Norma URP | <<locked>> | 80% | 45,934 psi | 72% | 3186 fps | 99.8% |
| Ramshot Grand | <<locked>> | 88% | 44,222 psi | 69% | 3222 fps | 96.1% |
| Ramshot Hunter | <<locked>> | 80% | 44,875 psi | 70% | 3176 fps | 99% |
| Ramshot Magnum | <<locked>> | 86% | 36,825 psi | 58% | 3002 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,297 psi | 44% | 2001 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 47,050 psi | 74% | 3222 fps | 99.9% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 45,223 psi | 71% | 3238 fps | 99.8% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 34,403 psi | 54% | 3012 fps | 95.1% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 48,675 psi | 76% | 3343 fps | 96% |
| Rottweil R 903 | <<locked>> | 80% | 53,911 psi | 84% | 3278 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 43,105 psi | 68% | 3091 fps | 95.3% |
| Rottweil R 905 | <<locked>> | 80% | 38,479 psi | 60% | 3022 fps | 95.2% |
| Rottweil R 907 | <<locked>> | 80% | 49,284 psi | 77% | 3205 fps | 98.8% |
| Shooters World Long Rifle | <<locked>> | 80% | 48,399 psi | 76% | 3179 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 80% | 46,717 psi | 73% | 3163 fps | 98.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 53,621 psi | 84% | 3140 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 47,210 psi | 74% | 3114 fps | 98.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 38,145 psi | 60% | 3018 fps | 95% |
| Somchem S355 | <<locked>> | 80% | 53,664 psi | 84% | 3274 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 47,123 psi | 74% | 3140 fps | 95.7% |
| Somchem S365 | <<locked>> | 80% | 42,989 psi | 67% | 3133 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 38,972 psi | 61% | 3002 fps | 96.3% |
| Vihtavuori N150 | <<locked>> | 80% | 51,358 psi | 80% | 3182 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 47,340 psi | 74% | 3179 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 84% | 38,725 psi | 61% | 2986 fps | 95.9% |
| Vihtavuori N550 | <<locked>> | 80% | 46,862 psi | 73% | 3182 fps | 99.8% |
| Vihtavuori N555 | <<locked>> | 80% | 37,782 psi | 59% | 3022 fps | 99.2% |
| Vihtavuori N560 | <<locked>> | 86% | 45,542 psi | 71% | 3245 fps | 95.4% |
| Vihtavuori N565 | <<locked>> | 92% | 46,021 psi | 72% | 3232 fps | 95.9% |
| Vihtavuori N568 | <<locked>> | 98% | 49,545 psi | 78% | 3353 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 46,659 psi | 73% | 3130 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 48,747 psi | 76% | 3258 fps | 99.1% |
| Winchester StaBALL HD | 59.6 gr | 80% | 30,008 psi | 47% | 2940 fps | 99.3% |
| Winchester Supreme 780 | <<locked>> | 82% | 38,305 psi | 60% | 2979 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 | Nosler Ballistic Tip Hunting. Hodgdon Retumbo delivers the highest muzzle velocity at 3,563 fps; across all powders the maximum-charge window runs from 2,178 fps to 3,563 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 1:10.0 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. Alliant Reloder-25, Winchester StaBALL HD, Accurate High Country rank at the top here: for .257 Weath. Mag. with the .257 | 100gr | Nosler Ballistic Tip Hunting 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.