Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 75gr | Barnes X bullet and 71 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, Alliant Reloder-16 and Hodgdon H414.
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.
A valid access license is required to use the Personalized Load Calculator.
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 2700 | <<locked>> | 82% | 56,811 psi | 89% | 3655 fps | 97.7% |
| Accurate 3100 | <<locked>> | 98% | 57,319 psi | 90% | 3714 fps | 99.2% |
| Accurate 4064 | <<locked>> | 82% | 57,580 psi | 90% | 3684 fps | 100% |
| Accurate 4350 | <<locked>> | 88% | 54,766 psi | 86% | 3720 fps | 99.7% |
| ADI AR 2208 | <<locked>> | 84% | 55,724 psi | 87% | 3691 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 94% | 54,868 psi | 86% | 3740 fps | 96.6% |
| Alliant Power Pro Varmint | <<locked>> | 94% | 55,259 psi | 87% | 3740 fps | 96.8% |
| Alliant Power Pro Varmint | <<locked>> | 94% | 55,259 psi | 87% | 3740 fps | 96.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 57,101 psi | 89% | 3727 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 57,319 psi | 90% | 3757 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 54,520 psi | 85% | 3780 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 86% | 56,101 psi | 88% | 3812 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 54,607 psi | 86% | 3727 fps | 96.7% |
| Alliant Reloder-22 | <<locked>> | 98% | 56,333 psi | 88% | 3799 fps | 97.2% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 56,956 psi | 89% | 3796 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 49,734 psi | 78% | 3694 fps | 98.9% |
| Alliant Reloder-26 | <<locked>> | 94% | 53,911 psi | 84% | 3819 fps | 99.7% |
| Bofors RP15ᴾ | <<locked>> | 100% | 55,259 psi | 87% | 3776 fps | 96.8% |
| Bofors RP3 | <<locked>> | 82% | 55,100 psi | 86% | 3688 fps | 100% |
| Bofors RP5 | <<locked>> | 98% | 56,333 psi | 88% | 3799 fps | 97.2% |
| Bofors RP7 | <<locked>> | 88% | 57,609 psi | 90% | 3720 fps | 98.1% |
| Hodgdon H380 | <<locked>> | 82% | 55,129 psi | 86% | 3698 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 88% | 56,086 psi | 88% | 3763 fps | 98.3% |
| Hodgdon H4350 | <<locked>> | 86% | 55,317 psi | 87% | 3714 fps | 97% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 55,332 psi | 87% | 3694 fps | 100% |
| Hodgdon Superformance | <<locked>> | 88% | 56,681 psi | 89% | 3793 fps | 98.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,767 psi | 58% | 2474 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 55,230 psi | 87% | 3675 fps | 99.9% |
| IMR 4350 | <<locked>> | 90% | 55,027 psi | 86% | 3678 fps | 97.7% |
| IMR 4451 Enduron | <<locked>> | 86% | 55,085 psi | 86% | 3675 fps | 98% |
| IMR 4831 | <<locked>> | 90% | 55,056 psi | 86% | 3704 fps | 99.7% |
| Lovex S062 | <<locked>> | 82% | 55,927 psi | 88% | 3678 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 56,246 psi | 88% | 3688 fps | 99.2% |
| Lovex S070 | <<locked>> | 90% | 57,696 psi | 90% | 3734 fps | 98.7% |
| Lovex S071ᴾ | <<locked>> | 100% | 51,213 psi | 80% | 3599 fps | 98.3% |
| Norma 203B | <<locked>> | 82% | 56,724 psi | 89% | 3737 fps | 100% |
| Norma 204 | <<locked>> | 90% | 55,970 psi | 88% | 3734 fps | 96.7% |
| Norma MRP | <<locked>> | 96% | 56,144 psi | 88% | 3832 fps | 98.4% |
| Norma URP | <<locked>> | 90% | 56,521 psi | 89% | 3760 fps | 99.8% |
| Ramshot Big Game | <<locked>> | 82% | 57,653 psi | 90% | 3760 fps | 100% |
| Ramshot Hunter | <<locked>> | 90% | 55,303 psi | 87% | 3743 fps | 98.9% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 53,519 psi | 84% | 3701 fps | 97.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,376 psi | 59% | 2526 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 54,737 psi | 86% | 3665 fps | 98.5% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 55,187 psi | 86% | 3806 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 54,476 psi | 85% | 3730 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 56,376 psi | 88% | 3829 fps | 99.7% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 49,545 psi | 78% | 3727 fps | 97.6% |
| Rottweil R 903 | <<locked>> | 84% | 55,376 psi | 87% | 3688 fps | 100% |
| Rottweil R 905 | <<locked>> | 96% | 57,624 psi | 90% | 3786 fps | 97.4% |
| Rottweil R 907 | <<locked>> | 88% | 57,609 psi | 90% | 3720 fps | 98.1% |
| Shooters World Long Rifle | <<locked>> | 88% | 56,246 psi | 88% | 3688 fps | 99.2% |
| Shooters World Precision | <<locked>> | 82% | 55,927 psi | 88% | 3678 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 57,696 psi | 90% | 3734 fps | 98.7% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 56,217 psi | 88% | 3737 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 55,100 psi | 86% | 3547 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 55,709 psi | 87% | 3619 fps | 98.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 96% | 57,145 psi | 90% | 3776 fps | 97.3% |
| Somchem S355 | <<locked>> | 84% | 54,882 psi | 86% | 3678 fps | 100% |
| Somchem S365 | <<locked>> | 92% | 56,405 psi | 88% | 3766 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 55,245 psi | 87% | 3694 fps | 97.7% |
| Vihtavuori N150 | <<locked>> | 86% | 56,101 psi | 88% | 3642 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 54,650 psi | 86% | 3681 fps | 99.6% |
| Vihtavuori N165 | <<locked>> | 98% | 54,244 psi | 85% | 3648 fps | 97.2% |
| Vihtavuori N540 | <<locked>> | 82% | 56,826 psi | 89% | 3648 fps | 100% |
| Vihtavuori N550 | <<locked>> | 88% | 54,230 psi | 85% | 3688 fps | 99.5% |
| Vihtavuori N555 | <<locked>> | 96% | 56,246 psi | 88% | 3773 fps | 100% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 54,447 psi | 85% | 3632 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 56,376 psi | 88% | 3766 fps | 98.4% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 53,592 psi | 84% | 3878 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 55,071 psi | 86% | 3675 fps | 96.7% |
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% | 53,069 psi | 83% | 3583 fps | 97% |
| Accurate 3100 | <<locked>> | 88% | 41,249 psi | 65% | 3373 fps | 95.8% |
| Accurate 4064 | <<locked>> | 80% | 53,998 psi | 85% | 3622 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 41,974 psi | 66% | 3442 fps | 97.6% |
| ADI AR 2208 | <<locked>> | 80% | 49,385 psi | 77% | 3566 fps | 99.4% |
| ADI AR 2209 | <<locked>> | 92% | 51,605 psi | 81% | 3671 fps | 95.8% |
| Alliant Power Pro Varmint | <<locked>> | 90% | 48,646 psi | 76% | 3596 fps | 95% |
| Alliant Power Pro Varmint | <<locked>> | 90% | 48,646 psi | 76% | 3596 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 50,633 psi | 79% | 3606 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 53,722 psi | 84% | 3684 fps | 99.8% |
| Alliant Reloder-16 | 56.8 gr | 80% | 39,740 psi | 62% | 3435 fps | 97.3% |
| Alliant Reloder-17 | <<locked>> | 80% | 45,484 psi | 71% | 3596 fps | 99.7% |
| Alliant Reloder-19 | <<locked>> | 92% | 51,387 psi | 81% | 3661 fps | 95.9% |
| Alliant Reloder-22 | <<locked>> | 94% | 49,443 psi | 77% | 3658 fps | 95.5% |
| Alliant Reloder-23 | <<locked>> | 80% | 30,139 psi | 47% | 3127 fps | 95% |
| Alliant Reloder-25 | <<locked>> | 92% | 38,711 psi | 61% | 3406 fps | 95.6% |
| Alliant Reloder-26 | 65.8 gr | 84% | 37,536 psi | 59% | 3419 fps | 95.9% |
| Bofors RP15 | <<locked>> | 96% | 48,515 psi | 76% | 3632 fps | 95.1% |
| Bofors RP3 | <<locked>> | 80% | 51,576 psi | 81% | 3622 fps | 100% |
| Bofors RP5 | <<locked>> | 94% | 49,443 psi | 77% | 3658 fps | 95.5% |
| Bofors RP7 | <<locked>> | 80% | 44,918 psi | 70% | 3445 fps | 95.1% |
| Hodgdon H380 | <<locked>> | 80% | 51,634 psi | 81% | 3629 fps | 99.1% |
| Hodgdon H414 | 59.8 gr | 80% | 43,105 psi | 68% | 3474 fps | 95.1% |
| Hodgdon H4350 | <<locked>> | 82% | 48,602 psi | 76% | 3570 fps | 95.3% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 37,492 psi | 59% | 3307 fps | 98.1% |
| Hodgdon Superformance | <<locked>> | 82% | 45,614 psi | 71% | 3560 fps | 95.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,427 psi | 43% | 2221 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 51,938 psi | 81% | 3609 fps | 99.7% |
| IMR 4350 | <<locked>> | 84% | 45,759 psi | 72% | 3478 fps | 95.4% |
| IMR 4451 Enduron | <<locked>> | 80% | 45,948 psi | 72% | 3474 fps | 95.9% |
| IMR 4831 | <<locked>> | 80% | 39,856 psi | 62% | 3366 fps | 97.1% |
| Lovex S062 | <<locked>> | 80% | 52,649 psi | 83% | 3615 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 43,976 psi | 69% | 3422 fps | 96.9% |
| Lovex S070 | <<locked>> | 80% | 42,453 psi | 67% | 3399 fps | 95.2% |
| Lovex S071 | <<locked>> | 92% | 39,943 psi | 63% | 3340 fps | 95.3% |
| Norma 203B | <<locked>> | 80% | 53,156 psi | 83% | 3671 fps | 99.9% |
| Norma 204 | <<locked>> | 88% | 52,344 psi | 82% | 3661 fps | 95.8% |
| Norma MRP | <<locked>> | 90% | 45,701 psi | 72% | 3606 fps | 96% |
| Norma URP | <<locked>> | 80% | 40,988 psi | 64% | 3422 fps | 97.2% |
| Ramshot Big Game | <<locked>> | 80% | 53,737 psi | 84% | 3688 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 80% | 39,813 psi | 62% | 3389 fps | 95% |
| Ramshot Magnum | <<locked>> | 96% | 46,412 psi | 73% | 3547 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,021 psi | 44% | 2277 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 51,401 psi | 81% | 3596 fps | 97.9% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 48,080 psi | 75% | 3668 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 41,510 psi | 65% | 3445 fps | 97.2% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 39,914 psi | 63% | 3442 fps | 96.3% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 43,120 psi | 68% | 3553 fps | 95.2% |
| Rottweil R 903 | <<locked>> | 80% | 48,733 psi | 76% | 3556 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 92% | 50,807 psi | 80% | 3645 fps | 95.9% |
| Rottweil R 907 | <<locked>> | 80% | 44,918 psi | 70% | 3445 fps | 95.1% |
| Shooters World Long Rifle | <<locked>> | 80% | 43,976 psi | 69% | 3422 fps | 96.9% |
| Shooters World Precision | <<locked>> | 80% | 52,649 psi | 83% | 3615 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 42,453 psi | 67% | 3399 fps | 95.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 49,356 psi | 77% | 3602 fps | 99.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 48,675 psi | 76% | 3435 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 43,207 psi | 68% | 3350 fps | 95.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 50,372 psi | 79% | 3638 fps | 95.7% |
| Somchem S355 | <<locked>> | 80% | 48,457 psi | 76% | 3550 fps | 99.8% |
| Somchem S365 | <<locked>> | 80% | 37,652 psi | 59% | 3369 fps | 99.2% |
| Somchem S385 | <<locked>> | 88% | 45,411 psi | 71% | 3481 fps | 95.3% |
| Vihtavuori N150 | <<locked>> | 80% | 46,456 psi | 73% | 3458 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 42,279 psi | 66% | 3415 fps | 97.5% |
| Vihtavuori N165 | <<locked>> | 94% | 47,703 psi | 75% | 3510 fps | 95.6% |
| Vihtavuori N540 | <<locked>> | 80% | 53,359 psi | 84% | 3586 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 42,119 psi | 66% | 3422 fps | 97.4% |
| Vihtavuori N555 | <<locked>> | 80% | 33,663 psi | 53% | 3238 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 41,655 psi | 65% | 3373 fps | 99.3% |
| Winchester 760 | <<locked>> | 80% | 43,308 psi | 68% | 3481 fps | 95.2% |
| Winchester StaBALL HD | <<locked>> | 82% | 29,008 psi | 45% | 3166 fps | 95% |
| Winchester Supreme 780 | <<locked>> | 94% | 51,329 psi | 80% | 3599 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 71 powders for .257 Weath. Mag. loaded with the .257 | 75gr | Barnes X. Winchester StaBALL HD delivers the highest muzzle velocity at 3,878 fps; across all powders the maximum-charge window runs from 2,474 fps to 3,878 fps. Alliant Reloder-23 gives the best case fill at 100 %, and 71 of the 71 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 75.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-23, Alliant Reloder-25, Bofors RP15 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, Alliant Reloder-16, Hodgdon H414 rank at the top here: for .257 Weath. Mag. with the .257 | 75gr | Barnes X 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.