Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 87gr | Hornady SP bullet and 77 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, Norma MRP and Vihtavuori N560.
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% | 55,405 psi | 87% | 3504 fps | 99.7% |
| Accurate 4350 | <<locked>> | 88% | 56,623 psi | 89% | 3566 fps | 100% |
| ADI AR 2208 | <<locked>> | 82% | 54,041 psi | 85% | 3471 fps | 100% |
| ADI AR 2209 | <<locked>> | 94% | 57,638 psi | 90% | 3615 fps | 98.4% |
| ADI AR 2213 | <<locked>> | 96% | 55,492 psi | 87% | 3606 fps | 97% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 41,278 psi | 65% | 3327 fps | 96.7% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 54,099 psi | 85% | 3540 fps | 97.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 55,274 psi | 87% | 3504 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 57,145 psi | 90% | 3632 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 54,868 psi | 86% | 3589 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 57,174 psi | 90% | 3602 fps | 98.4% |
| Alliant Reloder-22 | <<locked>> | 96% | 55,274 psi | 87% | 3602 fps | 98.2% |
| Alliant Reloder-23 | <<locked>> | 98% | 56,101 psi | 88% | 3586 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 51,909 psi | 81% | 3570 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 94% | 57,014 psi | 89% | 3684 fps | 100% |
| Bofors RP15 | <<locked>> | 98% | 54,201 psi | 85% | 3579 fps | 98% |
| Bofors RP3 | <<locked>> | 82% | 56,637 psi | 89% | 3524 fps | 100% |
| Bofors RP5 | <<locked>> | 96% | 55,274 psi | 87% | 3602 fps | 98.2% |
| Bofors RP7 | <<locked>> | 86% | 55,695 psi | 87% | 3507 fps | 98.8% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 51,126 psi | 80% | 3501 fps | 97% |
| Hodgdon H380 | <<locked>> | 82% | 56,637 psi | 89% | 3540 fps | 100% |
| Hodgdon H414 | <<locked>> | 86% | 54,766 psi | 86% | 3556 fps | 99.1% |
| Hodgdon H4350 | <<locked>> | 86% | 57,421 psi | 90% | 3576 fps | 98.6% |
| Hodgdon H4831 | <<locked>> | 94% | 55,274 psi | 87% | 3533 fps | 96.3% |
| Hodgdon H4831 SC | <<locked>> | 94% | 54,259 psi | 85% | 3517 fps | 96.1% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 57,638 psi | 90% | 3540 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 50,865 psi | 80% | 3625 fps | 98.3% |
| Hodgdon Superformance | <<locked>> | 86% | 55,259 psi | 87% | 3589 fps | 99% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,724 psi | 58% | 2320 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 56,898 psi | 89% | 3517 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 57,232 psi | 90% | 3543 fps | 99.1% |
| IMR 4451 Enduron | <<locked>> | 86% | 57,174 psi | 90% | 3537 fps | 99.3% |
| IMR 4831 | <<locked>> | 90% | 56,898 psi | 89% | 3553 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 56,579 psi | 89% | 3527 fps | 96.8% |
| IMR 7828 SSC | <<locked>> | 98% | 57,000 psi | 89% | 3648 fps | 97.5% |
| Lovex S062 | <<locked>> | 82% | 57,508 psi | 90% | 3507 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 57,667 psi | 90% | 3533 fps | 99.9% |
| Lovex S070 | <<locked>> | 88% | 55,796 psi | 87% | 3520 fps | 99.3% |
| Lovex S071ᴾ | <<locked>> | 100% | 52,794 psi | 83% | 3458 fps | 99.4% |
| Norma 204 | <<locked>> | 88% | 54,636 psi | 86% | 3533 fps | 97.8% |
| Norma MRP | <<locked>> | 94% | 54,955 psi | 86% | 3625 fps | 99.2% |
| Norma URP | <<locked>> | 88% | 54,998 psi | 86% | 3547 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 53,548 psi | 84% | 3589 fps | 97.1% |
| Ramshot Hunter | <<locked>> | 88% | 54,041 psi | 85% | 3540 fps | 99.5% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 56,550 psi | 89% | 3593 fps | 99.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,304 psi | 58% | 2369 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 56,333 psi | 88% | 3517 fps | 99.5% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 53,998 psi | 85% | 3579 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 56,594 psi | 89% | 3583 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 55,158 psi | 86% | 3619 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 51,938 psi | 81% | 3622 fps | 99.4% |
| Rottweil R 903 | <<locked>> | 84% | 56,739 psi | 89% | 3520 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 55,056 psi | 86% | 3510 fps | 97% |
| Rottweil R 905 | <<locked>> | 94% | 56,362 psi | 88% | 3583 fps | 98.4% |
| Rottweil R 907 | <<locked>> | 86% | 55,695 psi | 87% | 3507 fps | 98.8% |
| Shooters World Long Rifle | <<locked>> | 88% | 57,667 psi | 90% | 3533 fps | 99.9% |
| Shooters World Precision | <<locked>> | 82% | 57,508 psi | 90% | 3507 fps | 100% |
| Shooters World SW4350 | <<locked>> | 88% | 55,796 psi | 87% | 3520 fps | 99.3% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 54,752 psi | 86% | 3520 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 56,637 psi | 89% | 3379 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 57,145 psi | 90% | 3474 fps | 99.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 55,898 psi | 88% | 3576 fps | 98.3% |
| Somchem S355 | <<locked>> | 84% | 56,289 psi | 88% | 3514 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 57,290 psi | 90% | 3501 fps | 96.8% |
| Somchem S365 | <<locked>> | 90% | 55,187 psi | 86% | 3550 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 57,159 psi | 90% | 3556 fps | 99.1% |
| Vihtavuori N150 | <<locked>> | 86% | 57,740 psi | 90% | 3478 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 56,956 psi | 89% | 3540 fps | 100% |
| Vihtavuori N165 | <<locked>> | 98% | 56,811 psi | 89% | 3527 fps | 98.8% |
| Vihtavuori N550 | <<locked>> | 88% | 56,260 psi | 88% | 3540 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 54,694 psi | 86% | 3556 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 54,882 psi | 86% | 3615 fps | 96.5% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 54,795 psi | 86% | 3579 fps | 96.8% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 56,971 psi | 89% | 3488 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 54,766 psi | 86% | 3556 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 98% | 53,417 psi | 84% | 3665 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 57,363 psi | 90% | 3547 fps | 98.4% |
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% | 36,492 psi | 57% | 3094 fps | 95.7% |
| Accurate 4350 | <<locked>> | 80% | 42,583 psi | 67% | 3287 fps | 98.8% |
| ADI AR 2208 | <<locked>> | 80% | 50,792 psi | 80% | 3412 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 86% | 43,903 psi | 69% | 3330 fps | 95.2% |
| ADI AR 2213 | <<locked>> | 92% | 48,167 psi | 75% | 3455 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 98% | 38,696 psi | 61% | 3251 fps | 95.6% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 44,150 psi | 69% | 3330 fps | 95.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 51,909 psi | 81% | 3442 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 40,814 psi | 64% | 3294 fps | 98.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 47,311 psi | 74% | 3448 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 43,671 psi | 68% | 3320 fps | 95.2% |
| Alliant Reloder-22 | <<locked>> | 90% | 44,730 psi | 70% | 3383 fps | 95.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 30,371 psi | 48% | 2989 fps | 96.9% |
| Alliant Reloder-25 | <<locked>> | 88% | 34,664 psi | 54% | 3136 fps | 95.6% |
| Alliant Reloder-26 | 62.7 gr | 80% | 33,083 psi | 52% | 3127 fps | 95.6% |
| Bofors RP15 | <<locked>> | 92% | 44,324 psi | 69% | 3369 fps | 95.4% |
| Bofors RP3 | <<locked>> | 80% | 52,837 psi | 83% | 3458 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 44,730 psi | 70% | 3383 fps | 95.7% |
| Bofors RP7 | <<locked>> | 80% | 45,905 psi | 72% | 3304 fps | 96.9% |
| Hodgdon H1000 | <<locked>> | 98% | 47,819 psi | 75% | 3425 fps | 96.1% |
| Hodgdon H380 | <<locked>> | 80% | 52,910 psi | 83% | 3471 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 80% | 44,541 psi | 70% | 3343 fps | 97.2% |
| Hodgdon H4350 | <<locked>> | 80% | 47,108 psi | 74% | 3366 fps | 96.5% |
| Hodgdon H4831 | <<locked>> | 92% | 51,779 psi | 81% | 3468 fps | 95.4% |
| Hodgdon H4831 SC | <<locked>> | 92% | 50,575 psi | 79% | 3442 fps | 95.1% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 38,406 psi | 60% | 3159 fps | 99.2% |
| Hodgdon Retumbo | <<locked>> | 94% | 41,437 psi | 65% | 3383 fps | 95.1% |
| Hodgdon Superformance | <<locked>> | 80% | 44,034 psi | 69% | 3353 fps | 96.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,456 psi | 43% | 2087 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 53,403 psi | 84% | 3455 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 41,292 psi | 65% | 3205 fps | 95.6% |
| IMR 4451 Enduron | <<locked>> | 80% | 47,094 psi | 74% | 3337 fps | 97.7% |
| IMR 4831 | <<locked>> | 80% | 40,785 psi | 64% | 3225 fps | 98.6% |
| IMR 4955 Enduron | <<locked>> | 90% | 49,763 psi | 78% | 3392 fps | 95.1% |
| IMR 7828 SSC | <<locked>> | 94% | 49,632 psi | 78% | 3497 fps | 95.6% |
| Lovex S062 | <<locked>> | 80% | 54,012 psi | 85% | 3451 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 44,802 psi | 70% | 3278 fps | 98.3% |
| Lovex S070 | <<locked>> | 80% | 43,033 psi | 67% | 3251 fps | 96.9% |
| Lovex S071 | <<locked>> | 88% | 35,462 psi | 56% | 3064 fps | 95.2% |
| Norma 204 | <<locked>> | 82% | 44,353 psi | 70% | 3314 fps | 95.2% |
| Norma MRP | 65.4 gr | 86% | 40,959 psi | 64% | 3320 fps | 96% |
| Norma URP | <<locked>> | 80% | 41,989 psi | 66% | 3274 fps | 98.7% |
| Ramshot Grand | <<locked>> | 92% | 46,180 psi | 72% | 3428 fps | 95% |
| Ramshot Hunter | <<locked>> | 80% | 40,901 psi | 64% | 3255 fps | 97% |
| Ramshot Magnum | <<locked>> | 92% | 41,437 psi | 65% | 3274 fps | 95.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,862 psi | 44% | 2129 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 52,765 psi | 83% | 3451 fps | 99.2% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 50,183 psi | 79% | 3510 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 42,612 psi | 67% | 3304 fps | 98.7% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 40,973 psi | 64% | 3310 fps | 98.2% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 38,537 psi | 60% | 3281 fps | 95.3% |
| Rottweil R 903 | <<locked>> | 80% | 49,603 psi | 78% | 3392 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 48,457 psi | 76% | 3376 fps | 95.4% |
| Rottweil R 905 | <<locked>> | 86% | 42,888 psi | 67% | 3297 fps | 95.1% |
| Rottweil R 907 | <<locked>> | 80% | 45,905 psi | 72% | 3304 fps | 96.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 44,802 psi | 70% | 3278 fps | 98.3% |
| Shooters World Precision | <<locked>> | 80% | 54,012 psi | 85% | 3451 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 43,033 psi | 67% | 3251 fps | 96.9% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 50,952 psi | 80% | 3451 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 50,082 psi | 78% | 3274 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 43,976 psi | 69% | 3212 fps | 97.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 42,511 psi | 67% | 3291 fps | 95% |
| Somchem S355 | <<locked>> | 80% | 49,632 psi | 78% | 3389 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 49,995 psi | 78% | 3360 fps | 95% |
| Somchem S365 | <<locked>> | 80% | 38,682 psi | 61% | 3219 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 40,741 psi | 64% | 3209 fps | 95.4% |
| Vihtavuori N150 | <<locked>> | 80% | 47,471 psi | 74% | 3301 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 43,352 psi | 68% | 3271 fps | 98.9% |
| Vihtavuori N165 | <<locked>> | 90% | 43,178 psi | 68% | 3251 fps | 95.9% |
| Vihtavuori N550 | <<locked>> | 80% | 42,931 psi | 67% | 3271 fps | 98.7% |
| Vihtavuori N555 | <<locked>> | 80% | 33,939 psi | 53% | 3084 fps | 97% |
| Vihtavuori N560 | 70 gr | 92% | 51,140 psi | 80% | 3537 fps | 95.5% |
| Vihtavuori N565 | <<locked>> | 98% | 51,053 psi | 80% | 3504 fps | 95.9% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 42,772 psi | 67% | 3228 fps | 99.9% |
| Winchester 760 | <<locked>> | 80% | 44,541 psi | 70% | 3343 fps | 97.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 26,948 psi | 42% | 2949 fps | 95.8% |
| Winchester Supreme 780 | <<locked>> | 88% | 43,047 psi | 67% | 3255 fps | 95.1% |
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 77 powders for .257 Weath. Mag. loaded with the .257 | 87gr | Hornady SP. Alliant Reloder-26 delivers the highest muzzle velocity at 3,684 fps; across all powders the maximum-charge window runs from 2,320 fps to 3,684 fps. ADI AR 2225 gives the best case fill at 100 %, and 77 of the 77 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 1:11.5 twist; slower twists will usually not stabilise this weight. ADI AR 2225, Alliant Reloder-25, 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. Alliant Reloder-26, Norma MRP, Vihtavuori N560 rank at the top here: for .257 Weath. Mag. with the .257 | 87gr | Hornady SP 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.