Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 87gr | Speer MHP bullet and 80 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Norma MRP, Vihtavuori N560 and Alliant Reloder-26.
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 3100 | <<locked>> | 96% | 55,680 psi | 87% | 3510 fps | 99.7% |
| Accurate 4350 | <<locked>> | 88% | 56,985 psi | 89% | 3573 fps | 100% |
| Accurate High Country | <<locked>> | 94% | 57,363 psi | 90% | 3681 fps | 97.7% |
| ADI AR 2208 | <<locked>> | 82% | 54,360 psi | 85% | 3478 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 53,998 psi | 85% | 3550 fps | 97.9% |
| ADI AR 2213 | <<locked>> | 96% | 55,738 psi | 87% | 3615 fps | 97.1% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 41,669 psi | 65% | 3337 fps | 96.9% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 54,375 psi | 85% | 3547 fps | 97.9% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 54,375 psi | 85% | 3547 fps | 97.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 55,637 psi | 87% | 3507 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 57,479 psi | 90% | 3638 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 54,940 psi | 86% | 3589 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 57,450 psi | 90% | 3609 fps | 98.5% |
| Alliant Reloder-22 | <<locked>> | 96% | 55,564 psi | 87% | 3609 fps | 98.3% |
| Alliant Reloder-23 | <<locked>> | 98% | 56,391 psi | 88% | 3589 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 52,446 psi | 82% | 3583 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 94% | 57,363 psi | 90% | 3691 fps | 100% |
| Bofors RP15 | <<locked>> | 98% | 54,462 psi | 85% | 3586 fps | 98% |
| Bofors RP3 | <<locked>> | 82% | 56,710 psi | 89% | 3524 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 48,414 psi | 76% | 3481 fps | 96.1% |
| Bofors RP5 | <<locked>> | 96% | 55,564 psi | 87% | 3609 fps | 98.3% |
| Bofors RP7 | <<locked>> | 86% | 55,753 psi | 87% | 3510 fps | 98.9% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 51,648 psi | 81% | 3514 fps | 97.2% |
| Hodgdon H380 | <<locked>> | 82% | 56,927 psi | 89% | 3547 fps | 100% |
| Hodgdon H414 | <<locked>> | 86% | 54,824 psi | 86% | 3560 fps | 99.1% |
| Hodgdon H4350 | <<locked>> | 86% | 57,711 psi | 90% | 3583 fps | 98.7% |
| Hodgdon H4831 | <<locked>> | 94% | 55,811 psi | 87% | 3547 fps | 96.5% |
| Hodgdon H4831 SC | <<locked>> | 94% | 54,534 psi | 85% | 3520 fps | 96.2% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 54,302 psi | 85% | 3484 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 51,343 psi | 80% | 3638 fps | 98.5% |
| Hodgdon Superformance | <<locked>> | 86% | 55,535 psi | 87% | 3593 fps | 99.1% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,709 psi | 58% | 2323 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 57,246 psi | 90% | 3520 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 57,522 psi | 90% | 3550 fps | 99.1% |
| IMR 4451 Enduron | <<locked>> | 86% | 57,232 psi | 90% | 3537 fps | 99.3% |
| IMR 4831 | <<locked>> | 90% | 57,203 psi | 90% | 3560 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 56,826 psi | 89% | 3530 fps | 96.9% |
| IMR 7828 SSC | <<locked>> | 98% | 57,261 psi | 90% | 3655 fps | 97.5% |
| Lovex S062 | <<locked>> | 82% | 57,580 psi | 90% | 3510 fps | 100% |
| Lovex S065 | <<locked>> | 86% | 54,302 psi | 85% | 3474 fps | 99.7% |
| Lovex S070 | <<locked>> | 88% | 56,086 psi | 88% | 3527 fps | 99.4% |
| Lovex S071ᴾ | <<locked>> | 100% | 53,084 psi | 83% | 3465 fps | 99.5% |
| Norma 204 | <<locked>> | 88% | 54,926 psi | 86% | 3540 fps | 97.9% |
| Norma MRP | <<locked>> | 94% | 55,521 psi | 87% | 3638 fps | 99.3% |
| Norma URP | <<locked>> | 88% | 55,303 psi | 87% | 3550 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 54,085 psi | 85% | 3599 fps | 97.3% |
| Ramshot Hunter | <<locked>> | 88% | 54,331 psi | 85% | 3547 fps | 99.5% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 56,826 psi | 89% | 3599 fps | 99.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,492 psi | 59% | 2375 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 56,652 psi | 89% | 3524 fps | 99.6% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 54,331 psi | 85% | 3583 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 56,913 psi | 89% | 3593 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 55,463 psi | 87% | 3622 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 52,199 psi | 82% | 3629 fps | 99.4% |
| Rottweil R 903 | <<locked>> | 84% | 57,058 psi | 89% | 3527 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 55,332 psi | 87% | 3517 fps | 97.1% |
| Rottweil R 905 | <<locked>> | 94% | 56,652 psi | 89% | 3589 fps | 98.5% |
| Rottweil R 907 | <<locked>> | 86% | 55,753 psi | 87% | 3510 fps | 98.9% |
| Shooters World Long Rifle | <<locked>> | 86% | 54,302 psi | 85% | 3474 fps | 99.7% |
| Shooters World Precision | <<locked>> | 82% | 57,580 psi | 90% | 3510 fps | 100% |
| Shooters World SW4350 | <<locked>> | 88% | 56,086 psi | 88% | 3527 fps | 99.4% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 54,839 psi | 86% | 3524 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 56,942 psi | 89% | 3386 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 57,450 psi | 90% | 3481 fps | 99.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 56,202 psi | 88% | 3583 fps | 98.4% |
| Somchem S355 | <<locked>> | 84% | 56,594 psi | 89% | 3517 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 57,493 psi | 90% | 3501 fps | 96.8% |
| Somchem S365 | <<locked>> | 90% | 55,535 psi | 87% | 3556 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 57,435 psi | 90% | 3560 fps | 99.1% |
| Vihtavuori N150 | <<locked>> | 84% | 54,491 psi | 85% | 3425 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 57,217 psi | 90% | 3543 fps | 100% |
| Vihtavuori N165 | <<locked>> | 98% | 57,043 psi | 89% | 3530 fps | 98.9% |
| Vihtavuori N550 | <<locked>> | 88% | 56,550 psi | 89% | 3547 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 55,013 psi | 86% | 3563 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 55,419 psi | 87% | 3625 fps | 96.7% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 55,056 psi | 86% | 3586 fps | 96.9% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 57,232 psi | 90% | 3494 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 55,027 psi | 86% | 3563 fps | 99.2% |
| Winchester StaBALL HD | <<locked>> | 98% | 53,766 psi | 84% | 3671 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 57,667 psi | 90% | 3550 fps | 98.5% |
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% | 36,593 psi | 57% | 3097 fps | 95.8% |
| Accurate 4350 | <<locked>> | 80% | 42,888 psi | 67% | 3294 fps | 98.9% |
| Accurate High Country | <<locked>> | 90% | 49,574 psi | 78% | 3524 fps | 95.9% |
| ADI AR 2208 | <<locked>> | 80% | 51,068 psi | 80% | 3419 fps | 100% |
| ADI AR 2209 | <<locked>> | 86% | 44,179 psi | 69% | 3337 fps | 95.3% |
| ADI AR 2213 | <<locked>> | 92% | 48,414 psi | 76% | 3461 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 98% | 38,928 psi | 61% | 3258 fps | 95.7% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 44,440 psi | 70% | 3333 fps | 95.4% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 44,440 psi | 70% | 3333 fps | 95.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 52,011 psi | 82% | 3442 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 41,133 psi | 64% | 3304 fps | 98.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 47,616 psi | 75% | 3455 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 43,961 psi | 69% | 3323 fps | 95.3% |
| Alliant Reloder-22 | <<locked>> | 90% | 45,005 psi | 71% | 3386 fps | 95.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 30,458 psi | 48% | 2992 fps | 97% |
| Alliant Reloder-25 | <<locked>> | 88% | 34,896 psi | 55% | 3143 fps | 95.8% |
| Alliant Reloder-26 | 63 gr | 80% | 33,330 psi | 52% | 3133 fps | 95.8% |
| Bofors RP15 | <<locked>> | 92% | 44,570 psi | 70% | 3376 fps | 95.5% |
| Bofors RP3 | <<locked>> | 80% | 52,939 psi | 83% | 3461 fps | 100% |
| Bofors RP30 | <<locked>> | 98% | 45,049 psi | 71% | 3409 fps | 95.1% |
| Bofors RP5 | <<locked>> | 90% | 45,005 psi | 71% | 3386 fps | 95.8% |
| Bofors RP7 | <<locked>> | 80% | 45,948 psi | 72% | 3304 fps | 97% |
| Hodgdon H1000 | <<locked>> | 96% | 44,759 psi | 70% | 3353 fps | 95% |
| Hodgdon H380 | <<locked>> | 80% | 53,200 psi | 83% | 3478 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 80% | 44,643 psi | 70% | 3343 fps | 97.2% |
| Hodgdon H4350 | <<locked>> | 80% | 47,210 psi | 74% | 3369 fps | 96.6% |
| Hodgdon H4831 | <<locked>> | 92% | 52,040 psi | 82% | 3474 fps | 95.5% |
| Hodgdon H4831 SC | <<locked>> | 92% | 50,836 psi | 80% | 3448 fps | 95.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 38,682 psi | 61% | 3169 fps | 99.3% |
| Hodgdon Retumbo | <<locked>> | 94% | 41,655 psi | 65% | 3389 fps | 95.3% |
| Hodgdon Superformance | <<locked>> | 80% | 44,295 psi | 69% | 3360 fps | 96.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,325 psi | 43% | 2083 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 53,737 psi | 84% | 3461 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 41,582 psi | 65% | 3215 fps | 95.8% |
| IMR 4451 Enduron | <<locked>> | 80% | 47,384 psi | 74% | 3343 fps | 97.8% |
| IMR 4831 | <<locked>> | 80% | 40,886 psi | 64% | 3228 fps | 98.6% |
| IMR 4955 Enduron | <<locked>> | 90% | 50,024 psi | 78% | 3399 fps | 95.2% |
| IMR 7828 SSC | <<locked>> | 94% | 49,879 psi | 78% | 3504 fps | 95.8% |
| Lovex S062 | <<locked>> | 80% | 54,114 psi | 85% | 3455 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 44,889 psi | 70% | 3278 fps | 98.4% |
| Lovex S070 | <<locked>> | 80% | 43,308 psi | 68% | 3258 fps | 97% |
| Lovex S071 | <<locked>> | 88% | 35,737 psi | 56% | 3071 fps | 95.4% |
| Norma 204 | <<locked>> | 82% | 44,411 psi | 70% | 3317 fps | 95.2% |
| Norma MRP | 64.2 gr | 84% | 38,406 psi | 60% | 3248 fps | 95% |
| Norma URP | <<locked>> | 80% | 42,279 psi | 66% | 3284 fps | 98.7% |
| Ramshot Grand | <<locked>> | 92% | 46,456 psi | 73% | 3435 fps | 95.1% |
| Ramshot Hunter | <<locked>> | 80% | 41,162 psi | 65% | 3261 fps | 97.1% |
| Ramshot Magnum | <<locked>> | 92% | 41,669 psi | 65% | 3284 fps | 95.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,891 psi | 44% | 2133 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 53,026 psi | 83% | 3455 fps | 99.2% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 50,531 psi | 79% | 3517 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 42,888 psi | 67% | 3307 fps | 98.7% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 41,263 psi | 65% | 3317 fps | 98.3% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 38,711 psi | 61% | 3287 fps | 95.4% |
| Rottweil R 903 | <<locked>> | 80% | 49,966 psi | 78% | 3399 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 48,733 psi | 76% | 3383 fps | 95.5% |
| Rottweil R 905 | <<locked>> | 86% | 43,134 psi | 68% | 3307 fps | 95.3% |
| Rottweil R 907 | <<locked>> | 80% | 45,948 psi | 72% | 3304 fps | 97% |
| Shooters World Long Rifle | <<locked>> | 80% | 44,889 psi | 70% | 3278 fps | 98.4% |
| Shooters World Precision | <<locked>> | 80% | 54,114 psi | 85% | 3455 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 43,308 psi | 68% | 3258 fps | 97% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 51,242 psi | 80% | 3458 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 50,169 psi | 79% | 3274 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 43,976 psi | 69% | 3209 fps | 97.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 42,757 psi | 67% | 3297 fps | 95.1% |
| Somchem S355 | <<locked>> | 80% | 49,734 psi | 78% | 3392 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 50,227 psi | 79% | 3363 fps | 95.1% |
| Somchem S365 | <<locked>> | 80% | 39,015 psi | 61% | 3228 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 41,002 psi | 64% | 3215 fps | 95.5% |
| Vihtavuori N150 | <<locked>> | 80% | 47,761 psi | 75% | 3307 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 43,642 psi | 68% | 3278 fps | 99% |
| Vihtavuori N165 | <<locked>> | 88% | 40,698 psi | 64% | 3192 fps | 95% |
| Vihtavuori N550 | <<locked>> | 80% | 43,192 psi | 68% | 3278 fps | 98.8% |
| Vihtavuori N555 | <<locked>> | 80% | 34,214 psi | 54% | 3094 fps | 97.1% |
| Vihtavuori N560 | 70.3 gr | 92% | 51,416 psi | 81% | 3543 fps | 95.7% |
| Vihtavuori N565 | <<locked>> | 96% | 47,834 psi | 75% | 3435 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 43,047 psi | 67% | 3235 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 44,817 psi | 70% | 3350 fps | 97.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 27,137 psi | 43% | 2959 fps | 96% |
| Winchester Supreme 780 | <<locked>> | 88% | 43,308 psi | 68% | 3261 fps | 95.2% |
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 80 powders for .257 Weath. Mag. loaded with the .257 | 87gr | Speer MHP. Alliant Reloder-26 delivers the highest muzzle velocity at 3,691 fps; across all powders the maximum-charge window runs from 2,323 fps to 3,691 fps. ADI AR 2225 gives the best case fill at 100 %, and 80 of the 80 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 87.0 gr projectile in 0.257" calls for a 1:12.0 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. Norma MRP, Vihtavuori N560, Alliant Reloder-26 rank at the top here: for .257 Weath. Mag. with the .257 | 87gr | Speer MHP 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.