Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 85gr | Barnes X bullet and 75 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Winchester StaBALL HD, Ramshot Grand and IMR 7828 SSC.
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>> | 82% | 54,897 psi | 86% | 3445 fps | 98.4% |
| Accurate 3100 | <<locked>> | 94% | 54,868 psi | 86% | 3514 fps | 99.5% |
| Accurate 4350 | <<locked>> | 86% | 55,738 psi | 87% | 3570 fps | 100% |
| ADI AR 2208 | <<locked>> | 82% | 55,883 psi | 88% | 3527 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 55,767 psi | 87% | 3602 fps | 97.9% |
| ADI AR 2213 | <<locked>> | 96% | 57,363 psi | 90% | 3661 fps | 97.2% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 43,642 psi | 68% | 3402 fps | 97.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 57,537 psi | 90% | 3560 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 88% | 55,506 psi | 87% | 3629 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 56,898 psi | 89% | 3648 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 55,317 psi | 87% | 3586 fps | 97.9% |
| Alliant Reloder-22 | <<locked>> | 96% | 57,493 psi | 90% | 3665 fps | 98.4% |
| Alliant Reloder-23 | <<locked>> | 96% | 54,766 psi | 86% | 3586 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 54,128 psi | 85% | 3635 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 92% | 55,288 psi | 87% | 3681 fps | 100% |
| Bofors RP15 | <<locked>> | 98% | 56,420 psi | 88% | 3642 fps | 98.1% |
| Bofors RP30ᴾ | <<locked>> | 100% | 50,444 psi | 79% | 3547 fps | 96.4% |
| Bofors RP5 | <<locked>> | 96% | 57,493 psi | 90% | 3665 fps | 98.4% |
| Bofors RP7 | <<locked>> | 86% | 57,638 psi | 90% | 3560 fps | 98.9% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 49,719 psi | 78% | 3484 fps | 96.3% |
| Hodgdon H414 | <<locked>> | 82% | 54,157 psi | 85% | 3566 fps | 98.9% |
| Hodgdon H4350 | <<locked>> | 88% | 57,638 psi | 90% | 3596 fps | 98.4% |
| Hodgdon H4831 | <<locked>> | 98% | 56,637 psi | 89% | 3576 fps | 96.3% |
| Hodgdon H4831 SC | <<locked>> | 94% | 56,159 psi | 88% | 3570 fps | 96.2% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 55,985 psi | 88% | 3533 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 53,055 psi | 83% | 3694 fps | 98.6% |
| Hodgdon Superformance | <<locked>> | 86% | 57,566 psi | 90% | 3652 fps | 99.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,956 psi | 58% | 2339 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 55,085 psi | 86% | 3504 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 56,782 psi | 89% | 3530 fps | 99.1% |
| IMR 4350 | <<locked>> | 88% | 55,564 psi | 87% | 3530 fps | 98.7% |
| IMR 4451 Enduron | <<locked>> | 84% | 55,361 psi | 87% | 3520 fps | 98.9% |
| IMR 4831 | <<locked>> | 92% | 56,927 psi | 89% | 3573 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 54,897 psi | 86% | 3510 fps | 96.1% |
| IMR 7828 SSC | <<locked>> | 94% | 55,259 psi | 87% | 3635 fps | 96.8% |
| Lovex S065 | <<locked>> | 86% | 56,362 psi | 88% | 3527 fps | 99.7% |
| Lovex S070 | <<locked>> | 86% | 54,723 psi | 86% | 3517 fps | 99% |
| Lovex S071ᴾ | <<locked>> | 100% | 55,883 psi | 88% | 3530 fps | 99.6% |
| Norma 204 | <<locked>> | 88% | 56,521 psi | 89% | 3586 fps | 97.9% |
| Norma MRP | <<locked>> | 94% | 57,290 psi | 90% | 3691 fps | 99.3% |
| Norma URP | <<locked>> | 88% | 57,101 psi | 89% | 3606 fps | 100% |
| Ramshot Grand | <<locked>> | 92% | 55,172 psi | 86% | 3635 fps | 97.2% |
| Ramshot Hunter | <<locked>> | 88% | 56,057 psi | 88% | 3596 fps | 99.6% |
| Ramshot Magnum | <<locked>> | 96% | 56,695 psi | 89% | 3615 fps | 99% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,840 psi | 59% | 2395 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 56,144 psi | 88% | 3638 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 55,506 psi | 87% | 3583 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 57,130 psi | 90% | 3675 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 54,172 psi | 85% | 3691 fps | 99.5% |
| Rottweil R 903 | <<locked>> | 82% | 55,753 psi | 87% | 3520 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 57,101 psi | 89% | 3563 fps | 97.1% |
| Rottweil R 905 | <<locked>> | 92% | 54,969 psi | 86% | 3576 fps | 98% |
| Rottweil R 907 | <<locked>> | 86% | 57,638 psi | 90% | 3560 fps | 98.9% |
| Shooters World Long Rifle | <<locked>> | 86% | 56,362 psi | 88% | 3527 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 86% | 54,723 psi | 86% | 3517 fps | 99% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 56,681 psi | 89% | 3576 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 55,027 psi | 86% | 3373 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 55,811 psi | 87% | 3465 fps | 99.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 54,520 psi | 85% | 3570 fps | 97.8% |
| Somchem S355 | <<locked>> | 82% | 55,332 psi | 87% | 3514 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 55,434 psi | 87% | 3481 fps | 96.1% |
| Somchem S365 | <<locked>> | 90% | 57,508 psi | 90% | 3609 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 56,014 psi | 88% | 3550 fps | 98.7% |
| Unknown powder | <<locked>> | 86% | 57,334 psi | 90% | 3609 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 88% | 57,000 psi | 89% | 3491 fps | 100% |
| Vihtavuori N160 | <<locked>> | 84% | 54,172 psi | 85% | 3504 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 98% | 56,898 psi | 89% | 3547 fps | 98.6% |
| Vihtavuori N550 | <<locked>> | 84% | 54,766 psi | 86% | 3560 fps | 99.9% |
| Vihtavuori N555 | <<locked>> | 94% | 57,435 psi | 90% | 3622 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 57,508 psi | 90% | 3688 fps | 96.8% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 57,508 psi | 90% | 3648 fps | 97.1% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 54,897 psi | 86% | 3478 fps | 100% |
| Winchester 760 | <<locked>> | 82% | 54,157 psi | 85% | 3566 fps | 98.9% |
| Winchester StaBALL HD | <<locked>> | 98% | 55,883 psi | 88% | 3737 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 57,377 psi | 90% | 3563 fps | 98.2% |
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% | 51,343 psi | 80% | 3376 fps | 97.8% |
| Accurate 3100 | <<locked>> | 82% | 37,202 psi | 58% | 3123 fps | 95.7% |
| Accurate 4350 | <<locked>> | 80% | 45,687 psi | 72% | 3369 fps | 99.2% |
| ADI AR 2208 | <<locked>> | 80% | 52,620 psi | 82% | 3465 fps | 100% |
| ADI AR 2209 | <<locked>> | 86% | 45,788 psi | 72% | 3389 fps | 95.5% |
| ADI AR 2213 | <<locked>> | 92% | 50,343 psi | 79% | 3517 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 96% | 38,595 psi | 60% | 3258 fps | 95.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 54,201 psi | 85% | 3501 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 42,917 psi | 67% | 3363 fps | 99.1% |
| Alliant Reloder-17 | <<locked>> | 80% | 49,588 psi | 78% | 3514 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 45,890 psi | 72% | 3386 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 88% | 44,164 psi | 69% | 3383 fps | 95.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 32,938 psi | 52% | 3087 fps | 97.8% |
| Alliant Reloder-25 | <<locked>> | 86% | 34,853 psi | 55% | 3153 fps | 95.4% |
| Alliant Reloder-26 | <<locked>> | 80% | 35,926 psi | 56% | 3232 fps | 96.7% |
| Bofors RP15 | <<locked>> | 90% | 43,743 psi | 69% | 3373 fps | 95% |
| Bofors RP30 | <<locked>> | 98% | 47,340 psi | 74% | 3478 fps | 95.5% |
| Bofors RP5 | <<locked>> | 88% | 44,164 psi | 69% | 3383 fps | 95.2% |
| Bofors RP7 | <<locked>> | 80% | 48,167 psi | 75% | 3366 fps | 97.2% |
| Hodgdon H1000 | <<locked>> | 98% | 46,688 psi | 73% | 3415 fps | 95.3% |
| Hodgdon H414 | <<locked>> | 80% | 50,662 psi | 79% | 3494 fps | 98.3% |
| Hodgdon H4350 | <<locked>> | 80% | 45,237 psi | 71% | 3337 fps | 95.7% |
| Hodgdon H4831 | <<locked>> | 96% | 53,185 psi | 83% | 3510 fps | 95.5% |
| Hodgdon H4831 SC | <<locked>> | 92% | 52,707 psi | 83% | 3504 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 40,770 psi | 64% | 3232 fps | 99.5% |
| Hodgdon Retumbo | <<locked>> | 94% | 43,758 psi | 69% | 3461 fps | 95.8% |
| Hodgdon Superformance | <<locked>> | 80% | 46,093 psi | 72% | 3419 fps | 97.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,905 psi | 44% | 2106 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 51,851 psi | 81% | 3442 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 50,604 psi | 79% | 3406 fps | 98.2% |
| IMR 4350 | <<locked>> | 80% | 43,366 psi | 68% | 3271 fps | 96% |
| IMR 4451 Enduron | <<locked>> | 80% | 48,950 psi | 77% | 3392 fps | 97.8% |
| IMR 4831 | <<locked>> | 80% | 39,566 psi | 62% | 3209 fps | 98.1% |
| IMR 4955 Enduron | <<locked>> | 90% | 51,547 psi | 81% | 3445 fps | 95.3% |
| IMR 7828 SSC | 67.1 gr | 90% | 48,457 psi | 76% | 3491 fps | 95% |
| Lovex S065 | <<locked>> | 80% | 47,181 psi | 74% | 3346 fps | 98.6% |
| Lovex S070 | <<locked>> | 80% | 45,585 psi | 71% | 3323 fps | 97.4% |
| Lovex S071 | <<locked>> | 86% | 36,361 psi | 57% | 3100 fps | 95.4% |
| Norma 204 | <<locked>> | 82% | 46,296 psi | 73% | 3376 fps | 95.5% |
| Norma MRP | <<locked>> | 84% | 40,756 psi | 64% | 3330 fps | 95.7% |
| Norma URP | <<locked>> | 80% | 44,411 psi | 70% | 3346 fps | 99% |
| Ramshot Grand | 68.7 gr | 88% | 47,747 psi | 75% | 3478 fps | 95.2% |
| Ramshot Hunter | <<locked>> | 80% | 43,178 psi | 68% | 3323 fps | 97.4% |
| Ramshot Magnum | <<locked>> | 88% | 42,148 psi | 66% | 3307 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,384 psi | 44% | 2156 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 52,373 psi | 82% | 3573 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 45,281 psi | 71% | 3379 fps | 99% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 43,294 psi | 68% | 3386 fps | 98.6% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 41,060 psi | 64% | 3369 fps | 96.1% |
| Rottweil R 903 | <<locked>> | 80% | 52,431 psi | 82% | 3461 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 50,343 psi | 79% | 3432 fps | 95.6% |
| Rottweil R 905 | <<locked>> | 86% | 45,310 psi | 71% | 3373 fps | 95.6% |
| Rottweil R 907 | <<locked>> | 80% | 48,167 psi | 75% | 3366 fps | 97.2% |
| Shooters World Long Rifle | <<locked>> | 80% | 47,181 psi | 74% | 3346 fps | 98.6% |
| Shooters World SW4350 | <<locked>> | 80% | 45,585 psi | 71% | 3323 fps | 97.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 53,127 psi | 83% | 3510 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 51,982 psi | 81% | 3323 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 46,369 psi | 73% | 3278 fps | 97.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 44,904 psi | 70% | 3366 fps | 95.5% |
| Somchem S355 | <<locked>> | 80% | 52,112 psi | 82% | 3455 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 52,054 psi | 82% | 3415 fps | 95.2% |
| Somchem S365 | <<locked>> | 80% | 41,307 psi | 65% | 3301 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 40,683 psi | 64% | 3219 fps | 95.1% |
| Unknown powder | <<locked>> | 80% | 47,224 psi | 74% | 3409 fps | 99% |
| Vihtavuori N150 | <<locked>> | 80% | 44,817 psi | 70% | 3268 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 47,471 psi | 74% | 3376 fps | 99.4% |
| Vihtavuori N165 | <<locked>> | 88% | 41,379 psi | 65% | 3222 fps | 95% |
| Vihtavuori N550 | <<locked>> | 80% | 48,399 psi | 76% | 3435 fps | 99.4% |
| Vihtavuori N555 | <<locked>> | 80% | 36,927 psi | 58% | 3182 fps | 97.8% |
| Vihtavuori N560 | <<locked>> | 92% | 50,517 psi | 79% | 3547 fps | 95.1% |
| Vihtavuori N565 | <<locked>> | 96% | 50,357 psi | 79% | 3510 fps | 95.4% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 44,730 psi | 70% | 3287 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 50,662 psi | 79% | 3494 fps | 98.3% |
| Winchester StaBALL HD | 59.9 gr | 80% | 29,675 psi | 47% | 3077 fps | 97.5% |
| Winchester Supreme 780 | <<locked>> | 86% | 46,514 psi | 73% | 3350 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 82 powders for .257 Weath. Mag. loaded with the .257 | 85gr | Barnes X. Winchester StaBALL HD delivers the highest muzzle velocity at 3,737 fps; across all powders the maximum-charge window runs from 2,339 fps to 3,737 fps. ADI AR 2217 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 58–90 %, leaving at least 10 % headroom. The 85.0 gr projectile in 0.257" calls for a 1:11.0 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. Winchester StaBALL HD, Ramshot Grand, IMR 7828 SSC rank at the top here: for .257 Weath. Mag. with the .257 | 85gr | Barnes X they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Baschieri & Pellagri 109, IMR 8133 Enduron, Norma 217 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.