Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 90gr | Winchester Soft-Point bullet and 79 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, Ramshot Grand 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 2700 | <<locked>> | 84% | 57,101 psi | 89% | 3428 fps | 99.1% |
| Accurate 3100 | <<locked>> | 96% | 56,231 psi | 88% | 3474 fps | 99.8% |
| Accurate 4350 | <<locked>> | 88% | 57,334 psi | 90% | 3530 fps | 100% |
| ADI AR 2208 | <<locked>> | 82% | 54,694 psi | 86% | 3438 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 54,433 psi | 85% | 3514 fps | 98.1% |
| ADI AR 2213 | <<locked>> | 96% | 56,347 psi | 88% | 3583 fps | 97.5% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 41,974 psi | 66% | 3310 fps | 97.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 56,028 psi | 88% | 3468 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 88% | 54,404 psi | 85% | 3540 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 55,622 psi | 87% | 3553 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 54,114 psi | 85% | 3501 fps | 98.1% |
| Alliant Reloder-22 | <<locked>> | 96% | 56,173 psi | 88% | 3576 fps | 98.6% |
| Alliant Reloder-23 | <<locked>> | 98% | 57,029 psi | 89% | 3556 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 52,823 psi | 83% | 3543 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 53,708 psi | 84% | 3579 fps | 100% |
| Bofors RP15 | <<locked>> | 98% | 55,056 psi | 86% | 3556 fps | 98.3% |
| Bofors RP3 | <<locked>> | 82% | 57,188 psi | 90% | 3488 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 48,849 psi | 77% | 3451 fps | 96.5% |
| Bofors RP5 | <<locked>> | 96% | 56,173 psi | 88% | 3576 fps | 98.6% |
| Bofors RP7 | <<locked>> | 86% | 56,173 psi | 88% | 3471 fps | 99.1% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 48,356 psi | 76% | 3402 fps | 96.6% |
| Hodgdon H380 | <<locked>> | 82% | 57,421 psi | 90% | 3507 fps | 100% |
| Hodgdon H414 | <<locked>> | 84% | 56,434 psi | 88% | 3543 fps | 99.4% |
| Hodgdon H4350 | <<locked>> | 88% | 56,478 psi | 89% | 3514 fps | 98.7% |
| Hodgdon H4831 | <<locked>> | 98% | 55,303 psi | 87% | 3494 fps | 96.6% |
| Hodgdon H4831 SC | <<locked>> | 94% | 55,027 psi | 86% | 3488 fps | 96.5% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 54,607 psi | 86% | 3445 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 51,793 psi | 81% | 3606 fps | 98.8% |
| Hodgdon Superformance | <<locked>> | 86% | 56,057 psi | 88% | 3560 fps | 99.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,811 psi | 58% | 2283 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 57,624 psi | 90% | 3488 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 57,319 psi | 90% | 3474 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 55,637 psi | 87% | 3445 fps | 99.3% |
| IMR 4350 | <<locked>> | 88% | 54,375 psi | 85% | 3448 fps | 98.9% |
| IMR 4451 Enduron | <<locked>> | 86% | 57,653 psi | 90% | 3501 fps | 99.5% |
| IMR 4831 | <<locked>> | 92% | 55,259 psi | 87% | 3481 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 57,246 psi | 90% | 3497 fps | 97.2% |
| IMR 7828 SSC | <<locked>> | 94% | 54,143 psi | 85% | 3550 fps | 97.1% |
| Lovex S065 | <<locked>> | 86% | 54,766 psi | 86% | 3435 fps | 99.8% |
| Lovex S070 | <<locked>> | 88% | 56,391 psi | 88% | 3484 fps | 99.5% |
| Lovex S071ᴾ | <<locked>> | 100% | 53,621 psi | 84% | 3432 fps | 99.6% |
| Norma 204 | <<locked>> | 88% | 55,303 psi | 87% | 3504 fps | 98.1% |
| Norma MRP | <<locked>> | 94% | 55,941 psi | 88% | 3602 fps | 99.5% |
| Norma URP | <<locked>> | 88% | 55,651 psi | 87% | 3510 fps | 100% |
| Ramshot Grand | <<locked>> | 92% | 53,954 psi | 85% | 3553 fps | 97.5% |
| Ramshot Hunter | <<locked>> | 88% | 54,723 psi | 86% | 3510 fps | 99.7% |
| Ramshot Magnum | <<locked>> | 96% | 55,347 psi | 87% | 3530 fps | 99.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,420 psi | 59% | 2333 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 57,130 psi | 90% | 3484 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 54,969 psi | 86% | 3547 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 57,682 psi | 90% | 3556 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 55,999 psi | 88% | 3586 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 52,794 psi | 83% | 3602 fps | 99.6% |
| Rottweil R 903 | <<locked>> | 84% | 57,537 psi | 90% | 3484 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 55,956 psi | 88% | 3484 fps | 97.4% |
| Rottweil R 905 | <<locked>> | 94% | 57,159 psi | 90% | 3553 fps | 98.7% |
| Rottweil R 907 | <<locked>> | 86% | 56,173 psi | 88% | 3471 fps | 99.1% |
| Shooters World Long Rifle | <<locked>> | 86% | 54,766 psi | 86% | 3435 fps | 99.8% |
| Shooters World SW4350 | <<locked>> | 88% | 56,391 psi | 88% | 3484 fps | 99.5% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 55,317 psi | 87% | 3484 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 57,305 psi | 90% | 3343 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 54,201 psi | 85% | 3376 fps | 99.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 56,695 psi | 89% | 3550 fps | 98.6% |
| Somchem S355 | <<locked>> | 84% | 57,072 psi | 89% | 3478 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 54,099 psi | 85% | 3399 fps | 96.3% |
| Somchem S365 | <<locked>> | 90% | 55,970 psi | 88% | 3517 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 54,114 psi | 85% | 3458 fps | 98.8% |
| Unknown powder | <<locked>> | 86% | 56,043 psi | 88% | 3517 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 55,419 psi | 87% | 3399 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 56,478 psi | 89% | 3478 fps | 100% |
| Vihtavuori N165 | <<locked>> | 98% | 55,535 psi | 87% | 3461 fps | 98.8% |
| Vihtavuori N550 | <<locked>> | 86% | 56,913 psi | 89% | 3533 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 55,492 psi | 87% | 3524 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 56,347 psi | 88% | 3602 fps | 97.1% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 55,825 psi | 87% | 3560 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 57,740 psi | 90% | 3455 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 56,434 psi | 88% | 3543 fps | 99.4% |
| Winchester StaBALL HD | <<locked>> | 98% | 54,679 psi | 86% | 3642 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 55,811 psi | 87% | 3474 fps | 98.4% |
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 2700 | <<locked>> | 80% | 49,777 psi | 78% | 3291 fps | 98% |
| Accurate 3100 | <<locked>> | 82% | 34,577 psi | 54% | 3002 fps | 95.2% |
| Accurate 4350 | <<locked>> | 80% | 43,279 psi | 68% | 3258 fps | 99.1% |
| ADI AR 2208 | <<locked>> | 80% | 51,372 psi | 81% | 3376 fps | 100% |
| ADI AR 2209 | <<locked>> | 86% | 44,425 psi | 70% | 3301 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 92% | 48,834 psi | 77% | 3428 fps | 95.6% |
| ADI AR 2225 | <<locked>> | 96% | 36,753 psi | 58% | 3156 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 52,576 psi | 82% | 3406 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 41,423 psi | 65% | 3268 fps | 99.2% |
| Alliant Reloder-17 | <<locked>> | 80% | 48,138 psi | 75% | 3419 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 44,425 psi | 70% | 3294 fps | 95.8% |
| Alliant Reloder-22 | <<locked>> | 88% | 42,467 psi | 67% | 3284 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 30,879 psi | 48% | 2969 fps | 97.4% |
| Alliant Reloder-25 | <<locked>> | 86% | 32,938 psi | 52% | 3045 fps | 95.1% |
| Alliant Reloder-26 | 62.2 gr | 80% | 33,750 psi | 53% | 3110 fps | 96.3% |
| Bofors RP15 | <<locked>> | 90% | 42,119 psi | 66% | 3274 fps | 95% |
| Bofors RP3 | <<locked>> | 80% | 53,606 psi | 84% | 3425 fps | 100% |
| Bofors RP30 | <<locked>> | 98% | 45,382 psi | 71% | 3376 fps | 95.5% |
| Bofors RP5 | <<locked>> | 88% | 42,467 psi | 67% | 3284 fps | 95.3% |
| Bofors RP7 | <<locked>> | 80% | 46,470 psi | 73% | 3274 fps | 97.4% |
| Hodgdon H1000 | <<locked>> | 98% | 45,208 psi | 71% | 3330 fps | 95.6% |
| Hodgdon H380 | <<locked>> | 80% | 53,606 psi | 84% | 3438 fps | 99.9% |
| Hodgdon H414 | <<locked>> | 80% | 49,168 psi | 77% | 3402 fps | 98.4% |
| Hodgdon H4350 | <<locked>> | 80% | 43,816 psi | 69% | 3248 fps | 95.9% |
| Hodgdon H4831 | <<locked>> | 96% | 51,735 psi | 81% | 3425 fps | 95.8% |
| Hodgdon H4831 SC | <<locked>> | 92% | 51,271 psi | 80% | 3415 fps | 95.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 39,001 psi | 61% | 3133 fps | 99.5% |
| Hodgdon Retumbo | <<locked>> | 94% | 42,090 psi | 66% | 3366 fps | 95.9% |
| Hodgdon Superformance | <<locked>> | 80% | 44,657 psi | 70% | 3327 fps | 97.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,470 psi | 43% | 2051 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 54,128 psi | 85% | 3425 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 50,459 psi | 79% | 3353 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 49,327 psi | 77% | 3320 fps | 98.4% |
| IMR 4350 | <<locked>> | 80% | 41,872 psi | 66% | 3179 fps | 96.1% |
| IMR 4451 Enduron | <<locked>> | 80% | 47,674 psi | 75% | 3304 fps | 98% |
| IMR 4831 | <<locked>> | 80% | 37,478 psi | 59% | 3097 fps | 98% |
| IMR 4955 Enduron | <<locked>> | 90% | 50,343 psi | 79% | 3363 fps | 95.6% |
| IMR 7828 SSC | <<locked>> | 90% | 46,891 psi | 73% | 3396 fps | 95.1% |
| Lovex S065 | <<locked>> | 80% | 45,368 psi | 71% | 3248 fps | 98.7% |
| Lovex S070 | <<locked>> | 80% | 43,627 psi | 68% | 3225 fps | 97.4% |
| Lovex S071 | <<locked>> | 88% | 36,143 psi | 57% | 3045 fps | 95.9% |
| Norma 204 | <<locked>> | 82% | 44,860 psi | 70% | 3287 fps | 95.7% |
| Norma MRP | <<locked>> | 84% | 38,899 psi | 61% | 3225 fps | 95.6% |
| Norma URP | <<locked>> | 80% | 42,627 psi | 67% | 3245 fps | 99% |
| Ramshot Grand | 68.5 gr | 88% | 46,253 psi | 72% | 3389 fps | 95.4% |
| Ramshot Hunter | <<locked>> | 80% | 41,539 psi | 65% | 3228 fps | 97.5% |
| Ramshot Magnum | <<locked>> | 88% | 40,321 psi | 63% | 3209 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,079 psi | 44% | 2100 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 53,461 psi | 84% | 3419 fps | 99.4% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 51,082 psi | 80% | 3478 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 43,352 psi | 68% | 3278 fps | 99% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 41,698 psi | 65% | 3287 fps | 98.6% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 39,218 psi | 61% | 3268 fps | 96.1% |
| Rottweil R 903 | <<locked>> | 80% | 50,299 psi | 79% | 3360 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 48,994 psi | 77% | 3346 fps | 95.8% |
| Rottweil R 905 | <<locked>> | 86% | 43,613 psi | 68% | 3278 fps | 95.7% |
| Rottweil R 907 | <<locked>> | 80% | 46,470 psi | 73% | 3274 fps | 97.4% |
| Shooters World Long Rifle | <<locked>> | 80% | 45,368 psi | 71% | 3248 fps | 98.7% |
| Shooters World SW4350 | <<locked>> | 80% | 43,627 psi | 68% | 3225 fps | 97.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 51,677 psi | 81% | 3419 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 50,604 psi | 79% | 3235 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 44,512 psi | 70% | 3179 fps | 97.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 43,236 psi | 68% | 3268 fps | 95.6% |
| Somchem S355 | <<locked>> | 80% | 50,270 psi | 79% | 3356 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 50,633 psi | 79% | 3333 fps | 95.5% |
| Somchem S365 | <<locked>> | 80% | 39,378 psi | 62% | 3196 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 38,653 psi | 61% | 3117 fps | 95% |
| Unknown powder | <<locked>> | 80% | 45,643 psi | 72% | 3314 fps | 99.1% |
| Vihtavuori N150 | <<locked>> | 80% | 43,163 psi | 68% | 3173 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 45,847 psi | 72% | 3278 fps | 99.4% |
| Vihtavuori N165 | <<locked>> | 88% | 39,653 psi | 62% | 3127 fps | 95% |
| Vihtavuori N550 | <<locked>> | 80% | 46,586 psi | 73% | 3333 fps | 99.5% |
| Vihtavuori N555 | <<locked>> | 80% | 34,548 psi | 54% | 3061 fps | 97.5% |
| Vihtavuori N560 | <<locked>> | 92% | 49,110 psi | 77% | 3458 fps | 95.3% |
| Vihtavuori N565 | <<locked>> | 96% | 48,399 psi | 76% | 3409 fps | 95.4% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 43,308 psi | 68% | 3199 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 49,168 psi | 77% | 3402 fps | 98.4% |
| Winchester StaBALL HD | 59.7 gr | 80% | 27,427 psi | 43% | 2940 fps | 96.7% |
| Winchester Supreme 780 | <<locked>> | 86% | 44,730 psi | 70% | 3255 fps | 95.9% |
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 79 powders for .257 Weath. Mag. loaded with the .257 | 90gr | Winchester Soft-Point. Winchester StaBALL HD delivers the highest muzzle velocity at 3,642 fps; across all powders the maximum-charge window runs from 2,283 fps to 3,642 fps. ADI AR 2225 gives the best case fill at 100 %, and 79 of the 79 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 90.0 gr projectile in 0.257" calls for a 1:11.0 twist; slower twists will usually not stabilise this weight. ADI AR 2225, Alliant Reloder-25, Bofors RP30 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-26, Ramshot Grand, Winchester StaBALL HD rank at the top here: for .257 Weath. Mag. with the .257 | 90gr | Winchester Soft-Point 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.