Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 86gr | Winchester SPRN bullet and 82 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Norma MRP, ADI AR 2213 and ReloadSwiss RS 70.
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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You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 96% | 54,273 psi | 85% | 3497 fps | 99.5% |
| Accurate 4064 | <<locked>> | 82% | 57,406 psi | 90% | 3504 fps | 100% |
| Accurate 4350 | <<locked>> | 88% | 55,419 psi | 87% | 3563 fps | 100% |
| Accurate High Country | <<locked>> | 94% | 55,651 psi | 87% | 3665 fps | 97.2% |
| Accurate MAGPRO | <<locked>> | 96% | 56,927 psi | 89% | 3665 fps | 96.1% |
| ADI AR 2208 | <<locked>> | 84% | 56,739 psi | 89% | 3533 fps | 100% |
| ADI AR 2209 | <<locked>> | 94% | 56,594 psi | 89% | 3612 fps | 98.1% |
| ADI AR 2213 | <<locked>> | 96% | 54,520 psi | 85% | 3599 fps | 96.6% |
| Alliant Power Pro Varmint | <<locked>> | 94% | 56,898 psi | 89% | 3609 fps | 98.2% |
| Alliant Power Pro Varmint | <<locked>> | 94% | 56,898 psi | 89% | 3609 fps | 98.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 54,462 psi | 85% | 3504 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 56,202 psi | 88% | 3635 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 57,696 psi | 90% | 3652 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 56,144 psi | 88% | 3599 fps | 98.1% |
| Alliant Reloder-22 | <<locked>> | 96% | 54,215 psi | 85% | 3596 fps | 97.9% |
| Alliant Reloder-23 | <<locked>> | 98% | 54,955 psi | 86% | 3583 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 50,908 psi | 80% | 3566 fps | 99.8% |
| Alliant Reloder-26 | <<locked>> | 94% | 55,492 psi | 87% | 3675 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 56,768 psi | 89% | 3642 fps | 98.3% |
| Bofors RP3 | <<locked>> | 82% | 55,506 psi | 87% | 3520 fps | 100% |
| Bofors RP5 | <<locked>> | 96% | 54,215 psi | 85% | 3596 fps | 97.9% |
| Bofors RP7 | <<locked>> | 86% | 54,665 psi | 86% | 3501 fps | 98.6% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 50,241 psi | 79% | 3491 fps | 96.6% |
| Hodgdon H380 | <<locked>> | 82% | 55,811 psi | 87% | 3540 fps | 99.9% |
| Hodgdon H414 | <<locked>> | 88% | 57,493 psi | 90% | 3622 fps | 99.3% |
| Hodgdon H4350 | <<locked>> | 86% | 56,405 psi | 88% | 3573 fps | 98.3% |
| Hodgdon H4831 | <<locked>> | 94% | 54,288 psi | 85% | 3527 fps | 95.9% |
| Hodgdon H4831 SC | <<locked>> | 96% | 57,217 psi | 90% | 3586 fps | 96.5% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 56,507 psi | 89% | 3537 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 49,893 psi | 78% | 3615 fps | 97.9% |
| Hodgdon Superformance | <<locked>> | 86% | 54,128 psi | 85% | 3583 fps | 98.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,666 psi | 57% | 2326 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 56,072 psi | 88% | 3517 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 56,217 psi | 88% | 3537 fps | 98.8% |
| IMR 4451 Enduron | <<locked>> | 86% | 56,173 psi | 88% | 3530 fps | 99.1% |
| IMR 4831 | <<locked>> | 90% | 55,782 psi | 87% | 3550 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 55,651 psi | 87% | 3520 fps | 96.4% |
| IMR 7828 SSC | <<locked>> | 98% | 55,912 psi | 88% | 3642 fps | 97.1% |
| Lovex S062 | <<locked>> | 82% | 56,666 psi | 89% | 3514 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 56,637 psi | 89% | 3530 fps | 99.8% |
| Lovex S070 | <<locked>> | 88% | 54,795 psi | 86% | 3517 fps | 99.1% |
| Lovex S071ᴾ | <<locked>> | 100% | 51,735 psi | 81% | 3451 fps | 99.2% |
| Norma 203B | <<locked>> | 82% | 57,551 psi | 90% | 3573 fps | 100% |
| Norma 204 | <<locked>> | 90% | 57,508 psi | 90% | 3602 fps | 98.1% |
| Norma MRP | <<locked>> | 94% | 53,853 psi | 84% | 3622 fps | 98.9% |
| Norma URP | <<locked>> | 88% | 53,925 psi | 85% | 3543 fps | 99.9% |
| Ramshot Grand | <<locked>> | 98% | 56,637 psi | 89% | 3661 fps | 97.6% |
| Ramshot Hunter | <<locked>> | 90% | 56,753 psi | 89% | 3606 fps | 99.7% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 55,129 psi | 86% | 3583 fps | 98.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,246 psi | 58% | 2379 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 55,593 psi | 87% | 3517 fps | 99.4% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 57,029 psi | 89% | 3645 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 55,738 psi | 87% | 3583 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 54,056 psi | 85% | 3612 fps | 99.9% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 50,778 psi | 80% | 3612 fps | 99.1% |
| Rottweil R 903 | <<locked>> | 84% | 55,854 psi | 88% | 3520 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 54,317 psi | 85% | 3507 fps | 96.6% |
| Rottweil R 905 | <<locked>> | 94% | 55,274 psi | 87% | 3576 fps | 98.1% |
| Rottweil R 907 | <<locked>> | 86% | 54,665 psi | 86% | 3501 fps | 98.6% |
| Shooters World Long Rifle | <<locked>> | 88% | 56,637 psi | 89% | 3530 fps | 99.8% |
| Shooters World Precision | <<locked>> | 82% | 56,666 psi | 89% | 3514 fps | 100% |
| Shooters World SW4350 | <<locked>> | 88% | 54,795 psi | 86% | 3517 fps | 99.1% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 57,464 psi | 90% | 3586 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 55,869 psi | 88% | 3386 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 56,478 psi | 89% | 3474 fps | 99.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 54,824 psi | 86% | 3573 fps | 98% |
| Somchem S355 | <<locked>> | 84% | 55,506 psi | 87% | 3510 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 56,144 psi | 88% | 3491 fps | 96.3% |
| Somchem S365 | <<locked>> | 92% | 57,740 psi | 90% | 3609 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 56,072 psi | 88% | 3550 fps | 98.8% |
| Vihtavuori N150 | <<locked>> | 86% | 56,927 psi | 89% | 3481 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 55,840 psi | 88% | 3537 fps | 100% |
| Vihtavuori N165 | <<locked>> | 98% | 55,535 psi | 87% | 3514 fps | 98.5% |
| Vihtavuori N540 | <<locked>> | 82% | 57,624 psi | 90% | 3484 fps | 100% |
| Vihtavuori N550 | <<locked>> | 88% | 55,201 psi | 87% | 3540 fps | 99.9% |
| Vihtavuori N555 | <<locked>> | 96% | 57,145 psi | 90% | 3615 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 57,740 psi | 90% | 3681 fps | 97% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 53,737 psi | 84% | 3573 fps | 96.4% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 55,970 psi | 88% | 3488 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 57,493 psi | 90% | 3622 fps | 99.3% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 56,072 psi | 88% | 3727 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 56,376 psi | 88% | 3540 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>> | 84% | 35,636 psi | 56% | 3084 fps | 95.1% |
| Accurate 4064 | <<locked>> | 80% | 53,838 psi | 84% | 3445 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 41,756 psi | 65% | 3281 fps | 98.6% |
| Accurate High Country | <<locked>> | 90% | 48,225 psi | 76% | 3510 fps | 95.3% |
| Accurate MAGPRO | <<locked>> | 94% | 52,779 psi | 83% | 3579 fps | 95.1% |
| ADI AR 2208 | <<locked>> | 80% | 50,038 psi | 78% | 3409 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 88% | 46,166 psi | 72% | 3396 fps | 95.7% |
| ADI AR 2213 | 68.7 gr | 94% | 50,763 psi | 80% | 3524 fps | 95.6% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 46,412 psi | 73% | 3396 fps | 95.8% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 46,412 psi | 73% | 3396 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 51,097 psi | 80% | 3445 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 40,059 psi | 63% | 3291 fps | 98.6% |
| Alliant Reloder-17 | <<locked>> | 80% | 46,427 psi | 73% | 3448 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 45,890 psi | 72% | 3383 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 90% | 43,976 psi | 69% | 3376 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 29,762 psi | 47% | 2982 fps | 96.4% |
| Alliant Reloder-25 | <<locked>> | 88% | 34,069 psi | 53% | 3130 fps | 95.1% |
| Alliant Reloder-26 | <<locked>> | 80% | 32,401 psi | 51% | 3117 fps | 95.1% |
| Bofors RP15 | <<locked>> | 94% | 46,340 psi | 73% | 3428 fps | 95.9% |
| Bofors RP3 | <<locked>> | 80% | 52,011 psi | 82% | 3458 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 43,976 psi | 69% | 3376 fps | 95.3% |
| Bofors RP7 | <<locked>> | 80% | 45,208 psi | 71% | 3301 fps | 96.6% |
| Hodgdon H1000 | <<locked>> | 98% | 46,731 psi | 73% | 3412 fps | 95.5% |
| Hodgdon H380 | <<locked>> | 80% | 52,083 psi | 82% | 3471 fps | 99.7% |
| Hodgdon H414 | <<locked>> | 80% | 43,584 psi | 68% | 3333 fps | 96.7% |
| Hodgdon H4350 | <<locked>> | 80% | 46,398 psi | 73% | 3363 fps | 96.1% |
| Hodgdon H4831 | <<locked>> | 92% | 50,807 psi | 80% | 3461 fps | 95% |
| Hodgdon H4831 SC | <<locked>> | 94% | 53,272 psi | 83% | 3510 fps | 95.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 37,652 psi | 59% | 3156 fps | 99% |
| Hodgdon Retumbo | <<locked>> | 96% | 43,540 psi | 68% | 3455 fps | 95.8% |
| Hodgdon Superformance | <<locked>> | 80% | 43,062 psi | 67% | 3343 fps | 96.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,340 psi | 43% | 2090 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 52,605 psi | 82% | 3451 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 40,640 psi | 64% | 3202 fps | 95.2% |
| IMR 4451 Enduron | <<locked>> | 80% | 46,412 psi | 73% | 3333 fps | 97.3% |
| IMR 4831 | <<locked>> | 80% | 40,045 psi | 63% | 3222 fps | 98.3% |
| IMR 4955 Enduron | <<locked>> | 92% | 52,025 psi | 82% | 3451 fps | 95.5% |
| IMR 7828 SSC | <<locked>> | 94% | 48,414 psi | 76% | 3484 fps | 95.1% |
| Lovex S062 | <<locked>> | 80% | 53,214 psi | 83% | 3451 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 44,106 psi | 69% | 3274 fps | 98.1% |
| Lovex S070 | <<locked>> | 80% | 42,337 psi | 66% | 3248 fps | 96.6% |
| Lovex S071 | <<locked>> | 90% | 37,043 psi | 58% | 3120 fps | 95.7% |
| Norma 203B | <<locked>> | 80% | 53,780 psi | 84% | 3507 fps | 100% |
| Norma 204 | <<locked>> | 84% | 46,601 psi | 73% | 3383 fps | 95.7% |
| Norma MRP | 64.9 gr | 86% | 40,219 psi | 63% | 3317 fps | 95.6% |
| Norma URP | <<locked>> | 80% | 41,220 psi | 65% | 3271 fps | 98.4% |
| Ramshot Grand | <<locked>> | 94% | 48,704 psi | 76% | 3497 fps | 95.6% |
| Ramshot Hunter | <<locked>> | 80% | 40,161 psi | 63% | 3248 fps | 96.6% |
| Ramshot Magnum | <<locked>> | 92% | 40,582 psi | 64% | 3268 fps | 95.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,920 psi | 44% | 2142 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 51,996 psi | 81% | 3451 fps | 99% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 49,269 psi | 77% | 3510 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 41,814 psi | 66% | 3297 fps | 98.4% |
| ReloadSwiss RS 70 | 61.6 gr | 80% | 40,292 psi | 63% | 3307 fps | 97.8% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 40,495 psi | 63% | 3353 fps | 96% |
| Rottweil R 903 | <<locked>> | 80% | 48,791 psi | 76% | 3392 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 50,720 psi | 79% | 3435 fps | 95.8% |
| Rottweil R 905 | <<locked>> | 88% | 45,034 psi | 71% | 3363 fps | 95.6% |
| Rottweil R 907 | <<locked>> | 80% | 45,208 psi | 71% | 3301 fps | 96.6% |
| Shooters World Long Rifle | <<locked>> | 80% | 44,106 psi | 69% | 3274 fps | 98.1% |
| Shooters World Precision | <<locked>> | 80% | 53,214 psi | 83% | 3451 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 42,337 psi | 66% | 3248 fps | 96.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 50,125 psi | 79% | 3451 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 49,313 psi | 77% | 3278 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 43,279 psi | 68% | 3205 fps | 96.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 44,643 psi | 70% | 3356 fps | 95.5% |
| Somchem S355 | <<locked>> | 80% | 48,849 psi | 77% | 3389 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 52,518 psi | 82% | 3422 fps | 95.5% |
| Somchem S365 | <<locked>> | 80% | 37,869 psi | 59% | 3215 fps | 99.8% |
| Somchem S385 | <<locked>> | 84% | 40,074 psi | 63% | 3205 fps | 95% |
| Vihtavuori N150 | <<locked>> | 80% | 46,688 psi | 73% | 3297 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 42,583 psi | 67% | 3268 fps | 98.7% |
| Vihtavuori N165 | <<locked>> | 90% | 42,482 psi | 67% | 3248 fps | 95.4% |
| Vihtavuori N540 | <<locked>> | 80% | 53,954 psi | 85% | 3422 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 42,235 psi | 66% | 3271 fps | 98.4% |
| Vihtavuori N555 | <<locked>> | 80% | 33,199 psi | 52% | 3077 fps | 96.5% |
| Vihtavuori N560 | <<locked>> | 92% | 50,125 psi | 79% | 3530 fps | 95% |
| Vihtavuori N565 | <<locked>> | 98% | 50,009 psi | 78% | 3497 fps | 95.4% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 41,930 psi | 66% | 3225 fps | 99.9% |
| Winchester 760 | <<locked>> | 80% | 43,758 psi | 69% | 3337 fps | 96.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 26,411 psi | 41% | 2936 fps | 95.1% |
| Winchester Supreme 780 | <<locked>> | 90% | 45,353 psi | 71% | 3323 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 82 powders for .257 Weath. Mag. loaded with the .257 | 86gr | Winchester SPRN. Winchester StaBALL HD delivers the highest muzzle velocity at 3,727 fps; across all powders the maximum-charge window runs from 2,326 fps to 3,727 fps. Alliant Reloder-25 gives the best case fill at 100 %, and 82 of the 82 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 57–90 %, leaving at least 10 % headroom. The 86.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-25, Bofors RP15, Hodgdon H1000 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. Norma MRP, ADI AR 2213, ReloadSwiss RS 70 rank at the top here: for .257 Weath. Mag. with the .257 | 86gr | Winchester SPRN 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.