Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 90gr | Sierra Blitzking BT bullet and 76 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N560, Alliant Reloder-26 and Ramshot Grand.
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>> | 96% | 55,854 psi | 88% | 3471 fps | 99.8% |
| Accurate 4350 | <<locked>> | 88% | 57,217 psi | 90% | 3533 fps | 100% |
| Accurate MAGPRO | <<locked>> | 94% | 54,694 psi | 86% | 3563 fps | 96.1% |
| ADI AR 2208 | <<locked>> | 82% | 54,563 psi | 86% | 3438 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 54,288 psi | 85% | 3514 fps | 98.1% |
| ADI AR 2213 | <<locked>> | 96% | 55,970 psi | 88% | 3576 fps | 97.4% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 41,698 psi | 65% | 3301 fps | 97.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 55,898 psi | 88% | 3465 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 57,725 psi | 90% | 3596 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 55,448 psi | 87% | 3553 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 57,609 psi | 90% | 3566 fps | 98.7% |
| Alliant Reloder-22 | <<locked>> | 96% | 55,796 psi | 87% | 3573 fps | 98.5% |
| Alliant Reloder-23 | <<locked>> | 98% | 56,652 psi | 89% | 3550 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 52,475 psi | 82% | 3540 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 53,301 psi | 84% | 3576 fps | 100% |
| Bofors RP15 | <<locked>> | 98% | 54,694 psi | 86% | 3550 fps | 98.3% |
| Bofors RP3 | <<locked>> | 82% | 57,014 psi | 89% | 3481 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 48,501 psi | 76% | 3445 fps | 96.4% |
| Bofors RP5 | <<locked>> | 96% | 55,796 psi | 87% | 3573 fps | 98.5% |
| Bofors RP7 | <<locked>> | 86% | 56,057 psi | 88% | 3468 fps | 99% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 51,692 psi | 81% | 3471 fps | 97.4% |
| Hodgdon H380 | <<locked>> | 82% | 57,000 psi | 89% | 3501 fps | 100% |
| Hodgdon H414 | <<locked>> | 86% | 55,042 psi | 86% | 3520 fps | 99.3% |
| Hodgdon H4350 | <<locked>> | 84% | 54,360 psi | 85% | 3474 fps | 98.3% |
| Hodgdon H4831 | <<locked>> | 94% | 56,028 psi | 88% | 3507 fps | 96.7% |
| Hodgdon H4831 SC | <<locked>> | 94% | 54,665 psi | 86% | 3481 fps | 96.4% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 54,476 psi | 85% | 3442 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 51,430 psi | 81% | 3599 fps | 98.7% |
| Hodgdon Superformance | <<locked>> | 86% | 55,985 psi | 88% | 3556 fps | 99.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,782 psi | 58% | 2283 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 57,435 psi | 90% | 3474 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 57,740 psi | 90% | 3507 fps | 99.3% |
| IMR 4451 Enduron | <<locked>> | 86% | 57,537 psi | 90% | 3497 fps | 99.4% |
| IMR 4831 | <<locked>> | 90% | 57,464 psi | 90% | 3517 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 56,898 psi | 89% | 3491 fps | 97.1% |
| IMR 7828 SSC | <<locked>> | 98% | 57,551 psi | 90% | 3615 fps | 97.8% |
| Lovex S065 | <<locked>> | 86% | 54,607 psi | 86% | 3435 fps | 99.8% |
| Lovex S070 | <<locked>> | 88% | 56,289 psi | 88% | 3488 fps | 99.5% |
| Lovex S071ᴾ | <<locked>> | 100% | 53,214 psi | 83% | 3422 fps | 99.6% |
| Norma 204 | <<locked>> | 88% | 54,969 psi | 86% | 3497 fps | 98.1% |
| Norma MRP | <<locked>> | 94% | 55,521 psi | 87% | 3596 fps | 99.4% |
| Norma URP | <<locked>> | 88% | 55,506 psi | 87% | 3510 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 54,143 psi | 85% | 3560 fps | 97.5% |
| Ramshot Hunter | <<locked>> | 88% | 54,360 psi | 85% | 3504 fps | 99.6% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 57,000 psi | 89% | 3560 fps | 99.3% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,391 psi | 59% | 2329 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 56,768 psi | 89% | 3481 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 54,534 psi | 85% | 3540 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 57,290 psi | 90% | 3550 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 55,593 psi | 87% | 3579 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 52,475 psi | 82% | 3599 fps | 99.6% |
| Rottweil R 903 | <<locked>> | 84% | 57,116 psi | 90% | 3478 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 55,608 psi | 87% | 3478 fps | 97.3% |
| Rottweil R 905 | <<locked>> | 94% | 57,043 psi | 89% | 3553 fps | 98.7% |
| Rottweil R 907 | <<locked>> | 86% | 56,057 psi | 88% | 3468 fps | 99% |
| Shooters World Long Rifle | <<locked>> | 86% | 54,607 psi | 86% | 3435 fps | 99.8% |
| Shooters World SW4350 | <<locked>> | 88% | 56,289 psi | 88% | 3488 fps | 99.5% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 55,158 psi | 86% | 3484 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 57,116 psi | 90% | 3340 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 57,638 psi | 90% | 3438 fps | 99.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 56,579 psi | 89% | 3550 fps | 98.6% |
| Somchem S355 | <<locked>> | 84% | 56,898 psi | 89% | 3474 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 57,740 psi | 90% | 3465 fps | 97.1% |
| Somchem S365 | <<locked>> | 90% | 55,840 psi | 88% | 3514 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 57,566 psi | 90% | 3520 fps | 99.3% |
| Vihtavuori N150 | <<locked>> | 84% | 54,549 psi | 85% | 3383 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 57,435 psi | 90% | 3501 fps | 100% |
| Vihtavuori N165 | <<locked>> | 98% | 57,319 psi | 90% | 3491 fps | 99% |
| Vihtavuori N550 | <<locked>> | 88% | 56,782 psi | 89% | 3507 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 55,332 psi | 87% | 3527 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 55,419 psi | 87% | 3583 fps | 96.9% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 55,448 psi | 87% | 3550 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 57,377 psi | 90% | 3451 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 55,303 psi | 87% | 3524 fps | 99.3% |
| Winchester StaBALL HD | <<locked>> | 98% | 54,244 psi | 85% | 3635 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 53,838 psi | 84% | 3442 fps | 98.1% |
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>> | 82% | 34,432 psi | 54% | 2999 fps | 95.2% |
| Accurate 4350 | <<locked>> | 80% | 43,149 psi | 68% | 3258 fps | 99.1% |
| Accurate MAGPRO | <<locked>> | 92% | 50,691 psi | 79% | 3481 fps | 95% |
| ADI AR 2208 | <<locked>> | 80% | 51,213 psi | 80% | 3376 fps | 100% |
| ADI AR 2209 | <<locked>> | 86% | 44,295 psi | 69% | 3301 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 92% | 48,733 psi | 76% | 3425 fps | 95.6% |
| ADI AR 2225 | <<locked>> | 98% | 39,088 psi | 61% | 3228 fps | 96.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 52,431 psi | 82% | 3406 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 41,278 psi | 65% | 3264 fps | 99.1% |
| Alliant Reloder-17 | <<locked>> | 80% | 47,747 psi | 75% | 3412 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 44,121 psi | 69% | 3291 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 88% | 42,337 psi | 66% | 3284 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 30,763 psi | 48% | 2966 fps | 97.4% |
| Alliant Reloder-25 | <<locked>> | 86% | 32,837 psi | 51% | 3041 fps | 95% |
| Alliant Reloder-26 | 61.9 gr | 80% | 33,460 psi | 52% | 3104 fps | 96.2% |
| Bofors RP15 | <<locked>> | 92% | 44,628 psi | 70% | 3337 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 53,185 psi | 83% | 3419 fps | 100% |
| Bofors RP30 | <<locked>> | 98% | 45,281 psi | 71% | 3376 fps | 95.4% |
| Bofors RP5 | <<locked>> | 88% | 42,337 psi | 66% | 3284 fps | 95.3% |
| Bofors RP7 | <<locked>> | 80% | 46,108 psi | 72% | 3268 fps | 97.2% |
| Hodgdon H1000 | <<locked>> | 96% | 44,933 psi | 70% | 3323 fps | 95.4% |
| Hodgdon H380 | <<locked>> | 80% | 53,490 psi | 84% | 3438 fps | 99.9% |
| Hodgdon H414 | <<locked>> | 80% | 44,860 psi | 70% | 3307 fps | 97.5% |
| Hodgdon H4350 | <<locked>> | 80% | 47,427 psi | 74% | 3333 fps | 96.9% |
| Hodgdon H4831 | <<locked>> | 92% | 52,141 psi | 82% | 3432 fps | 95.8% |
| Hodgdon H4831 SC | <<locked>> | 92% | 51,169 psi | 80% | 3412 fps | 95.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 38,856 psi | 61% | 3130 fps | 99.5% |
| Hodgdon Retumbo | <<locked>> | 94% | 41,989 psi | 66% | 3363 fps | 95.8% |
| Hodgdon Superformance | <<locked>> | 80% | 44,541 psi | 70% | 3323 fps | 97.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,412 psi | 43% | 2047 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 53,882 psi | 84% | 3415 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 41,742 psi | 65% | 3179 fps | 96.1% |
| IMR 4451 Enduron | <<locked>> | 80% | 47,529 psi | 74% | 3301 fps | 98% |
| IMR 4831 | <<locked>> | 80% | 41,060 psi | 64% | 3189 fps | 98.8% |
| IMR 4955 Enduron | <<locked>> | 90% | 50,241 psi | 79% | 3363 fps | 95.6% |
| IMR 7828 SSC | <<locked>> | 92% | 46,572 psi | 73% | 3389 fps | 95% |
| Lovex S065 | <<locked>> | 80% | 45,223 psi | 71% | 3245 fps | 98.6% |
| Lovex S070 | <<locked>> | 80% | 43,511 psi | 68% | 3222 fps | 97.3% |
| Lovex S071 | <<locked>> | 88% | 35,795 psi | 56% | 3038 fps | 95.7% |
| Norma 204 | <<locked>> | 82% | 44,730 psi | 70% | 3284 fps | 95.6% |
| Norma MRP | <<locked>> | 84% | 38,595 psi | 60% | 3219 fps | 95.4% |
| Norma URP | <<locked>> | 80% | 42,496 psi | 67% | 3245 fps | 98.9% |
| Ramshot Grand | 68.6 gr | 92% | 46,862 psi | 73% | 3406 fps | 95.6% |
| Ramshot Hunter | <<locked>> | 80% | 41,408 psi | 65% | 3228 fps | 97.4% |
| Ramshot Magnum | <<locked>> | 92% | 41,858 psi | 66% | 3248 fps | 96.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,007 psi | 44% | 2096 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 53,098 psi | 83% | 3415 fps | 99.3% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 50,676 psi | 79% | 3474 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 43,221 psi | 68% | 3274 fps | 99% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 41,568 psi | 65% | 3287 fps | 98.6% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 38,943 psi | 61% | 3261 fps | 95.9% |
| Rottweil R 903 | <<locked>> | 80% | 50,140 psi | 79% | 3360 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 48,863 psi | 77% | 3346 fps | 95.8% |
| Rottweil R 905 | <<locked>> | 86% | 43,468 psi | 68% | 3274 fps | 95.7% |
| Rottweil R 907 | <<locked>> | 80% | 46,108 psi | 72% | 3268 fps | 97.2% |
| Shooters World Long Rifle | <<locked>> | 80% | 45,223 psi | 71% | 3245 fps | 98.6% |
| Shooters World SW4350 | <<locked>> | 80% | 43,511 psi | 68% | 3222 fps | 97.3% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 51,547 psi | 81% | 3419 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 50,459 psi | 79% | 3235 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 44,222 psi | 69% | 3176 fps | 97.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 43,091 psi | 68% | 3268 fps | 95.5% |
| Somchem S355 | <<locked>> | 80% | 50,125 psi | 79% | 3356 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 50,314 psi | 79% | 3327 fps | 95.4% |
| Somchem S365 | <<locked>> | 80% | 39,218 psi | 61% | 3192 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 41,321 psi | 65% | 3186 fps | 95.9% |
| Vihtavuori N150 | <<locked>> | 80% | 47,935 psi | 75% | 3264 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 43,859 psi | 69% | 3245 fps | 99.2% |
| Vihtavuori N165 | <<locked>> | 88% | 40,872 psi | 64% | 3159 fps | 95.4% |
| Vihtavuori N550 | <<locked>> | 80% | 43,453 psi | 68% | 3241 fps | 99% |
| Vihtavuori N555 | <<locked>> | 80% | 34,403 psi | 54% | 3061 fps | 97.4% |
| Vihtavuori N560 | 67.6 gr | 90% | 48,066 psi | 75% | 3432 fps | 95% |
| Vihtavuori N565 | <<locked>> | 96% | 48,095 psi | 75% | 3402 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 43,178 psi | 68% | 3199 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 45,107 psi | 71% | 3314 fps | 97.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 27,340 psi | 43% | 2936 fps | 96.7% |
| Winchester Supreme 780 | <<locked>> | 88% | 43,555 psi | 68% | 3232 fps | 95.6% |
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 76 powders for .257 Weath. Mag. loaded with the .257 | 90gr | Sierra Blitzking BT. Winchester StaBALL HD delivers the highest muzzle velocity at 3,635 fps; across all powders the maximum-charge window runs from 2,283 fps to 3,635 fps. ADI AR 2225 gives the best case fill at 100 %, and 76 of the 76 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 1:10.0 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. Vihtavuori N560, Alliant Reloder-26, Ramshot Grand rank at the top here: for .257 Weath. Mag. with the .257 | 90gr | Sierra Blitzking BT 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.