Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 95gr | Hammer HHT bullet and 79 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% | 55,492 psi | 87% | 3396 fps | 99.9% |
| Accurate 4350 | <<locked>> | 88% | 56,594 psi | 89% | 3451 fps | 100% |
| Accurate High Country | <<locked>> | 94% | 57,363 psi | 90% | 3570 fps | 98.3% |
| Accurate MAGPRO | <<locked>> | 94% | 54,404 psi | 85% | 3494 fps | 96.5% |
| ADI AR 2208 | <<locked>> | 82% | 54,520 psi | 85% | 3363 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 54,172 psi | 85% | 3442 fps | 98.4% |
| ADI AR 2213 | <<locked>> | 96% | 55,767 psi | 87% | 3504 fps | 97.8% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 41,321 psi | 65% | 3235 fps | 97.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 55,492 psi | 87% | 3386 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 88% | 53,969 psi | 85% | 3458 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 55,172 psi | 86% | 3474 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 57,522 psi | 90% | 3497 fps | 98.9% |
| Alliant Reloder-22 | <<locked>> | 96% | 55,477 psi | 87% | 3497 fps | 98.8% |
| Alliant Reloder-23 | <<locked>> | 98% | 56,536 psi | 89% | 3474 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 52,243 psi | 82% | 3468 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 94% | 57,551 psi | 90% | 3576 fps | 100% |
| Bofors RP15 | <<locked>> | 98% | 54,360 psi | 85% | 3474 fps | 98.5% |
| Bofors RP3 | <<locked>> | 82% | 56,550 psi | 89% | 3402 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 48,182 psi | 76% | 3376 fps | 96.8% |
| Bofors RP5 | <<locked>> | 96% | 55,477 psi | 87% | 3497 fps | 98.8% |
| Bofors RP7 | <<locked>> | 86% | 55,782 psi | 87% | 3392 fps | 99.2% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 51,503 psi | 81% | 3409 fps | 97.8% |
| Hodgdon H380 | <<locked>> | 82% | 56,681 psi | 89% | 3422 fps | 100% |
| Hodgdon H414 | <<locked>> | 86% | 54,969 psi | 86% | 3445 fps | 99.5% |
| Hodgdon H4350 | <<locked>> | 84% | 53,983 psi | 85% | 3399 fps | 98.6% |
| Hodgdon H4831 | <<locked>> | 94% | 55,695 psi | 87% | 3435 fps | 97.1% |
| Hodgdon H4831 SC | <<locked>> | 94% | 54,621 psi | 86% | 3415 fps | 96.9% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 54,375 psi | 85% | 3369 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 51,213 psi | 80% | 3527 fps | 99% |
| Hodgdon Superformance | <<locked>> | 86% | 55,680 psi | 87% | 3484 fps | 99.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,579 psi | 57% | 2218 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 57,392 psi | 90% | 3402 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 57,522 psi | 90% | 3435 fps | 99.5% |
| IMR 4451 Enduron | <<locked>> | 86% | 57,464 psi | 90% | 3425 fps | 99.6% |
| IMR 4831 | <<locked>> | 90% | 57,087 psi | 89% | 3438 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 56,840 psi | 89% | 3425 fps | 97.5% |
| IMR 7828 SSC | <<locked>> | 98% | 57,392 psi | 90% | 3547 fps | 98.2% |
| Lovex S062 | <<locked>> | 82% | 57,580 psi | 90% | 3389 fps | 100% |
| Lovex S065 | <<locked>> | 86% | 54,288 psi | 85% | 3360 fps | 99.9% |
| Lovex S070 | <<locked>> | 88% | 55,767 psi | 87% | 3406 fps | 99.6% |
| Lovex S071ᴾ | <<locked>> | 100% | 52,779 psi | 83% | 3350 fps | 99.7% |
| Norma 204 | <<locked>> | 88% | 55,013 psi | 86% | 3432 fps | 98.4% |
| Norma MRP | <<locked>> | 94% | 55,506 psi | 87% | 3527 fps | 99.6% |
| Norma URP | <<locked>> | 88% | 55,100 psi | 86% | 3432 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 53,969 psi | 85% | 3491 fps | 97.9% |
| Ramshot Hunter | <<locked>> | 88% | 54,360 psi | 85% | 3432 fps | 99.8% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 56,768 psi | 89% | 3491 fps | 99.5% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,391 psi | 59% | 2270 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 56,550 psi | 89% | 3406 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 54,505 psi | 85% | 3465 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 56,971 psi | 89% | 3474 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 55,535 psi | 87% | 3507 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 52,127 psi | 82% | 3524 fps | 99.7% |
| Rottweil R 903 | <<locked>> | 84% | 56,913 psi | 89% | 3402 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 55,390 psi | 87% | 3409 fps | 97.7% |
| Rottweil R 905 | <<locked>> | 94% | 56,869 psi | 89% | 3481 fps | 99% |
| Rottweil R 907 | <<locked>> | 86% | 55,782 psi | 87% | 3392 fps | 99.2% |
| Shooters World Long Rifle | <<locked>> | 86% | 54,288 psi | 85% | 3360 fps | 99.9% |
| Shooters World Precision | <<locked>> | 82% | 57,580 psi | 90% | 3389 fps | 100% |
| Shooters World SW4350 | <<locked>> | 88% | 55,767 psi | 87% | 3406 fps | 99.6% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 54,998 psi | 86% | 3409 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 57,087 psi | 89% | 3268 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 57,450 psi | 90% | 3366 fps | 99.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 56,434 psi | 88% | 3478 fps | 98.9% |
| Somchem S355 | <<locked>> | 84% | 56,507 psi | 89% | 3396 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 57,435 psi | 90% | 3396 fps | 97.4% |
| Somchem S365 | <<locked>> | 90% | 55,506 psi | 87% | 3435 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 57,363 psi | 90% | 3448 fps | 99.4% |
| Vihtavuori N150 | <<locked>> | 84% | 54,462 psi | 85% | 3307 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 57,116 psi | 90% | 3425 fps | 100% |
| Vihtavuori N165 | <<locked>> | 98% | 57,029 psi | 89% | 3419 fps | 99.2% |
| Vihtavuori N550 | <<locked>> | 88% | 56,434 psi | 88% | 3428 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 54,940 psi | 86% | 3445 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 55,434 psi | 87% | 3517 fps | 97.3% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 54,911 psi | 86% | 3478 fps | 97.5% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 57,334 psi | 90% | 3379 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 55,201 psi | 87% | 3451 fps | 99.5% |
| Winchester StaBALL HD | <<locked>> | 98% | 54,143 psi | 85% | 3560 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 57,653 psi | 90% | 3442 fps | 98.9% |
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>> | 82% | 33,692 psi | 53% | 2920 fps | 95.4% |
| Accurate 4350 | <<locked>> | 80% | 42,627 psi | 67% | 3182 fps | 99.3% |
| Accurate High Country | <<locked>> | 88% | 45,919 psi | 72% | 3337 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 92% | 50,546 psi | 79% | 3415 fps | 95.5% |
| ADI AR 2208 | <<locked>> | 80% | 51,068 psi | 80% | 3301 fps | 100% |
| ADI AR 2209 | <<locked>> | 84% | 41,147 psi | 64% | 3159 fps | 95.1% |
| ADI AR 2213 | <<locked>> | 92% | 48,544 psi | 76% | 3360 fps | 96.1% |
| ADI AR 2225 | <<locked>> | 96% | 36,143 psi | 57% | 3087 fps | 95.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 51,953 psi | 81% | 3323 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 41,060 psi | 64% | 3192 fps | 99.3% |
| Alliant Reloder-17 | <<locked>> | 80% | 47,529 psi | 74% | 3337 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 41,017 psi | 64% | 3153 fps | 95.2% |
| Alliant Reloder-22 | <<locked>> | 88% | 41,945 psi | 66% | 3212 fps | 95.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 30,139 psi | 47% | 2890 fps | 97.6% |
| Alliant Reloder-25 | <<locked>> | 86% | 32,387 psi | 51% | 2976 fps | 95.4% |
| Alliant Reloder-26 | 60.8 gr | 80% | 32,953 psi | 52% | 3028 fps | 96.5% |
| Bofors RP15 | <<locked>> | 90% | 41,321 psi | 65% | 3196 fps | 95.2% |
| Bofors RP3 | <<locked>> | 80% | 52,852 psi | 83% | 3340 fps | 100% |
| Bofors RP30 | <<locked>> | 98% | 44,846 psi | 70% | 3304 fps | 95.8% |
| Bofors RP5 | <<locked>> | 88% | 41,945 psi | 66% | 3212 fps | 95.6% |
| Bofors RP7 | <<locked>> | 80% | 45,818 psi | 72% | 3196 fps | 97.6% |
| Hodgdon H1000 | <<locked>> | 96% | 44,512 psi | 70% | 3255 fps | 95.9% |
| Hodgdon H380 | <<locked>> | 80% | 53,026 psi | 83% | 3360 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 44,527 psi | 70% | 3235 fps | 97.8% |
| Hodgdon H4350 | <<locked>> | 80% | 47,340 psi | 74% | 3264 fps | 97.3% |
| Hodgdon H4831 | <<locked>> | 90% | 48,341 psi | 76% | 3291 fps | 95.3% |
| Hodgdon H4831 SC | <<locked>> | 90% | 47,398 psi | 74% | 3271 fps | 95% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 38,508 psi | 60% | 3058 fps | 99.6% |
| Hodgdon Retumbo | <<locked>> | 94% | 41,524 psi | 65% | 3291 fps | 96.2% |
| Hodgdon Superformance | <<locked>> | 80% | 44,150 psi | 69% | 3255 fps | 97.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,412 psi | 43% | 1991 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 53,722 psi | 84% | 3340 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 41,539 psi | 65% | 3110 fps | 96.5% |
| IMR 4451 Enduron | <<locked>> | 80% | 47,398 psi | 74% | 3232 fps | 98.3% |
| IMR 4831 | <<locked>> | 80% | 40,683 psi | 64% | 3120 fps | 99% |
| IMR 4955 Enduron | <<locked>> | 88% | 46,818 psi | 73% | 3225 fps | 95.1% |
| IMR 7828 SSC | <<locked>> | 92% | 46,325 psi | 73% | 3320 fps | 95.5% |
| Lovex S062 | <<locked>> | 80% | 53,969 psi | 85% | 3330 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 44,643 psi | 70% | 3169 fps | 98.8% |
| Lovex S070 | <<locked>> | 80% | 43,134 psi | 68% | 3150 fps | 97.6% |
| Lovex S071 | <<locked>> | 86% | 32,837 psi | 51% | 2897 fps | 95% |
| Norma 204 | <<locked>> | 80% | 41,336 psi | 65% | 3140 fps | 95% |
| Norma MRP | 62 gr | 84% | 38,261 psi | 60% | 3150 fps | 95.8% |
| Norma URP | <<locked>> | 80% | 42,163 psi | 66% | 3173 fps | 99.1% |
| Ramshot Grand | <<locked>> | 92% | 46,441 psi | 73% | 3333 fps | 96% |
| Ramshot Hunter | <<locked>> | 80% | 41,060 psi | 64% | 3156 fps | 97.7% |
| Ramshot Magnum | <<locked>> | 90% | 38,493 psi | 60% | 3107 fps | 95.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,804 psi | 44% | 2034 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 52,779 psi | 83% | 3337 fps | 99.5% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 50,502 psi | 79% | 3396 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 42,772 psi | 67% | 3199 fps | 99.1% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 41,292 psi | 65% | 3215 fps | 98.8% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 38,464 psi | 60% | 3189 fps | 96.3% |
| Rottweil R 903 | <<locked>> | 80% | 49,748 psi | 78% | 3278 fps | 100% |
| Rottweil R 904 | <<locked>> | 86% | 45,571 psi | 71% | 3209 fps | 95.3% |
| Rottweil R 905 | <<locked>> | 84% | 40,059 psi | 63% | 3130 fps | 95% |
| Rottweil R 907 | <<locked>> | 80% | 45,818 psi | 72% | 3196 fps | 97.6% |
| Shooters World Long Rifle | <<locked>> | 80% | 44,643 psi | 70% | 3169 fps | 98.8% |
| Shooters World Precision | <<locked>> | 80% | 53,969 psi | 85% | 3330 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 43,134 psi | 68% | 3150 fps | 97.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 51,256 psi | 80% | 3343 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 50,212 psi | 79% | 3159 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 43,874 psi | 69% | 3107 fps | 97.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 42,598 psi | 67% | 3192 fps | 95.8% |
| Somchem S355 | <<locked>> | 80% | 49,559 psi | 78% | 3274 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 50,067 psi | 78% | 3261 fps | 95.8% |
| Somchem S365 | <<locked>> | 80% | 38,914 psi | 61% | 3117 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 37,985 psi | 60% | 3038 fps | 95.2% |
| Vihtavuori N150 | <<locked>> | 80% | 47,645 psi | 75% | 3189 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 43,613 psi | 68% | 3169 fps | 99.4% |
| Vihtavuori N165 | <<locked>> | 88% | 40,379 psi | 63% | 3087 fps | 95.7% |
| Vihtavuori N550 | <<locked>> | 80% | 42,989 psi | 67% | 3169 fps | 99.2% |
| Vihtavuori N555 | <<locked>> | 80% | 33,837 psi | 53% | 2982 fps | 97.7% |
| Vihtavuori N560 | 66.4 gr | 90% | 47,848 psi | 75% | 3363 fps | 95.4% |
| Vihtavuori N565 | <<locked>> | 96% | 47,616 psi | 75% | 3333 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 42,946 psi | 67% | 3130 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 44,744 psi | 70% | 3238 fps | 97.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 26,687 psi | 42% | 2861 fps | 96.9% |
| Winchester Supreme 780 | <<locked>> | 88% | 43,149 psi | 68% | 3159 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 86 powders for .257 Weath. Mag. loaded with the .257 | 95gr | Hammer HHT. Alliant Reloder-26 delivers the highest muzzle velocity at 3,576 fps; across all powders the maximum-charge window runs from 2,218 fps to 3,576 fps. ADI AR 2217 gives the best case fill at 100 %, and 86 of the 86 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 95.0 gr projectile in 0.257" calls for a 1:9.5 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. Norma MRP, Vihtavuori N560, Alliant Reloder-26 rank at the top here: for .257 Weath. Mag. with the .257 | 95gr | Hammer HHT 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.