Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 100gr | Hasler Hunting bullet and 78 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Winchester StaBALL HD, Vihtavuori N560 and Norma MRP.
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% | 55,419 psi | 87% | 3261 fps | 99.4% |
| Accurate 3100 | <<locked>> | 94% | 55,303 psi | 87% | 3323 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 56,202 psi | 88% | 3369 fps | 100% |
| Accurate MAGPRO | <<locked>> | 94% | 54,563 psi | 86% | 3419 fps | 96.4% |
| ADI AR 2208 | <<locked>> | 82% | 56,942 psi | 89% | 3327 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 57,203 psi | 90% | 3425 fps | 99.2% |
| ADI AR 2213 | <<locked>> | 94% | 55,085 psi | 86% | 3425 fps | 98.1% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 49,400 psi | 77% | 3297 fps | 97.3% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 44,251 psi | 69% | 3251 fps | 98.9% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 57,537 psi | 90% | 3422 fps | 99.2% |
| Alliant Reloder-16 | <<locked>> | 88% | 57,000 psi | 89% | 3432 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 54,346 psi | 85% | 3383 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 56,826 psi | 89% | 3412 fps | 99.2% |
| Alliant Reloder-22 | <<locked>> | 94% | 55,100 psi | 86% | 3419 fps | 99% |
| Alliant Reloder-23 | <<locked>> | 96% | 56,231 psi | 88% | 3396 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 55,709 psi | 87% | 3455 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 56,927 psi | 89% | 3491 fps | 100% |
| Bofors RP15 | <<locked>> | 96% | 54,070 psi | 85% | 3399 fps | 98.8% |
| Bofors RP30ᴾ | <<locked>> | 100% | 51,764 psi | 81% | 3379 fps | 98% |
| Bofors RP5 | <<locked>> | 94% | 55,100 psi | 86% | 3419 fps | 99% |
| Bofors RP7 | <<locked>> | 84% | 54,868 psi | 86% | 3304 fps | 99.4% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 50,763 psi | 80% | 3330 fps | 98.1% |
| Hodgdon H414 | <<locked>> | 82% | 55,085 psi | 86% | 3376 fps | 99.7% |
| Hodgdon H4350 | <<locked>> | 86% | 55,376 psi | 87% | 3353 fps | 99.1% |
| Hodgdon H4831 | <<locked>> | 96% | 54,418 psi | 85% | 3346 fps | 97.3% |
| Hodgdon H4831 SC | <<locked>> | 94% | 57,682 psi | 90% | 3402 fps | 97.9% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 57,479 psi | 90% | 3343 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 54,636 psi | 86% | 3530 fps | 99.7% |
| Hodgdon Superformance | <<locked>> | 84% | 54,897 psi | 86% | 3396 fps | 99.6% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,057 psi | 58% | 2172 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 55,927 psi | 88% | 3304 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 54,520 psi | 85% | 3284 fps | 99.6% |
| IMR 4350 | <<locked>> | 88% | 56,594 psi | 89% | 3346 fps | 99.6% |
| IMR 4451 Enduron | <<locked>> | 84% | 56,333 psi | 88% | 3337 fps | 99.7% |
| IMR 4831 | <<locked>> | 90% | 54,462 psi | 85% | 3323 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 55,941 psi | 88% | 3340 fps | 97.8% |
| IMR 7828 SSC | <<locked>> | 94% | 57,043 psi | 89% | 3471 fps | 98.5% |
| Lovex S065 | <<locked>> | 86% | 57,000 psi | 89% | 3333 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 55,317 psi | 87% | 3327 fps | 99.8% |
| Lovex S071ᴾ | <<locked>> | 100% | 56,405 psi | 88% | 3340 fps | 100% |
| Norma 204 | <<locked>> | 86% | 54,012 psi | 85% | 3343 fps | 98.6% |
| Norma 217ᴾ | <<locked>> | 100% | 39,697 psi | 62% | 3156 fps | 96.9% |
| Norma MRP | <<locked>> | 92% | 54,998 psi | 86% | 3445 fps | 99.7% |
| Norma URP | <<locked>> | 86% | 54,694 psi | 86% | 3350 fps | 100% |
| Ramshot Grand | <<locked>> | 92% | 57,000 psi | 89% | 3478 fps | 98.8% |
| Ramshot Hunter | <<locked>> | 88% | 57,406 psi | 90% | 3412 fps | 100% |
| Ramshot Magnum | <<locked>> | 94% | 54,143 psi | 85% | 3376 fps | 99.5% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,724 psi | 59% | 2218 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 56,318 psi | 88% | 3389 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 54,737 psi | 86% | 3422 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 55,898 psi | 88% | 3530 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 50,734 psi | 80% | 3386 fps | 96.4% |
| Rottweil R 903 | <<locked>> | 82% | 56,304 psi | 88% | 3317 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 54,549 psi | 85% | 3323 fps | 98% |
| Rottweil R 905 | <<locked>> | 92% | 56,275 psi | 88% | 3399 fps | 99.2% |
| Rottweil R 907 | <<locked>> | 84% | 54,868 psi | 86% | 3304 fps | 99.4% |
| Shooters World Long Rifle | <<locked>> | 86% | 57,000 psi | 89% | 3333 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 55,317 psi | 87% | 3327 fps | 99.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 56,028 psi | 88% | 3173 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 56,521 psi | 89% | 3281 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 55,840 psi | 88% | 3396 fps | 99.1% |
| Somchem S355 | <<locked>> | 82% | 55,724 psi | 87% | 3304 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 56,507 psi | 89% | 3314 fps | 97.7% |
| Somchem S365 | <<locked>> | 88% | 55,085 psi | 86% | 3350 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 56,869 psi | 89% | 3369 fps | 99.6% |
| Unknown powder | <<locked>> | 84% | 54,737 psi | 86% | 3350 fps | 100% |
| Vihtavuori N150 | <<locked>> | 86% | 54,346 psi | 85% | 3235 fps | 100% |
| Vihtavuori N160 | <<locked>> | 84% | 55,013 psi | 86% | 3310 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 54,346 psi | 85% | 3307 fps | 99.2% |
| Vihtavuori N550 | <<locked>> | 84% | 55,695 psi | 87% | 3366 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 54,839 psi | 86% | 3369 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 55,332 psi | 87% | 3448 fps | 97.8% |
| Vihtavuori N565 | <<locked>> | 98% | 54,882 psi | 86% | 3409 fps | 97.9% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 51,517 psi | 81% | 3392 fps | 96% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 56,086 psi | 88% | 3284 fps | 100% |
| Winchester 760 | <<locked>> | 82% | 55,085 psi | 86% | 3376 fps | 99.7% |
| Winchester StaBALL HD | <<locked>> | 96% | 54,186 psi | 85% | 3481 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 54,476 psi | 85% | 3320 fps | 98.8% |
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% | 51,779 psi | 81% | 3196 fps | 99% |
| Accurate 3100 | <<locked>> | 80% | 34,084 psi | 53% | 2867 fps | 96.1% |
| Accurate 4350 | <<locked>> | 80% | 45,687 psi | 72% | 3176 fps | 99.8% |
| Accurate MAGPRO | <<locked>> | 92% | 50,792 psi | 80% | 3343 fps | 95.4% |
| ADI AR 2208 | <<locked>> | 80% | 53,417 psi | 84% | 3268 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 40,770 psi | 64% | 3084 fps | 95.6% |
| ADI AR 2213 | <<locked>> | 88% | 44,701 psi | 70% | 3205 fps | 95.5% |
| ADI AR 2217 | <<locked>> | 96% | 43,076 psi | 68% | 3153 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 94% | 36,143 psi | 57% | 3031 fps | 96.1% |
| Alliant Power Pro Varmint | <<locked>> | 82% | 41,147 psi | 64% | 3087 fps | 95.8% |
| Alliant Reloder-16 | <<locked>> | 80% | 43,569 psi | 68% | 3179 fps | 99.8% |
| Alliant Reloder-17 | <<locked>> | 80% | 50,778 psi | 80% | 3323 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 40,756 psi | 64% | 3081 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 84% | 39,102 psi | 61% | 3074 fps | 95.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 32,677 psi | 51% | 2904 fps | 98.9% |
| Alliant Reloder-25 | <<locked>> | 82% | 30,472 psi | 48% | 2851 fps | 95.1% |
| Alliant Reloder-26 | <<locked>> | 80% | 35,810 psi | 56% | 3051 fps | 98.2% |
| Bofors RP15 | <<locked>> | 88% | 41,539 psi | 65% | 3133 fps | 95.9% |
| Bofors RP30 | <<locked>> | 94% | 42,047 psi | 66% | 3173 fps | 95.5% |
| Bofors RP5 | <<locked>> | 84% | 39,102 psi | 61% | 3074 fps | 95.2% |
| Bofors RP7 | <<locked>> | 80% | 48,428 psi | 76% | 3182 fps | 98.5% |
| Hodgdon H1000 | <<locked>> | 94% | 41,321 psi | 65% | 3117 fps | 95.4% |
| Hodgdon H414 | <<locked>> | 80% | 51,372 psi | 81% | 3307 fps | 99.3% |
| Hodgdon H4350 | <<locked>> | 80% | 45,832 psi | 72% | 3163 fps | 97.4% |
| Hodgdon H4831 | <<locked>> | 92% | 47,587 psi | 75% | 3212 fps | 95.7% |
| Hodgdon H4831 SC | <<locked>> | 88% | 46,905 psi | 74% | 3196 fps | 95.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 41,278 psi | 65% | 3051 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 38,856 psi | 61% | 3156 fps | 95.8% |
| Hodgdon Superformance | <<locked>> | 80% | 47,036 psi | 74% | 3245 fps | 98.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,644 psi | 43% | 1946 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 52,649 psi | 83% | 3245 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 51,169 psi | 80% | 3219 fps | 99.3% |
| IMR 4350 | <<locked>> | 80% | 43,830 psi | 69% | 3097 fps | 97.6% |
| IMR 4451 Enduron | <<locked>> | 80% | 49,632 psi | 78% | 3209 fps | 99% |
| IMR 4831 | <<locked>> | 80% | 39,421 psi | 62% | 3018 fps | 99.1% |
| IMR 4955 Enduron | <<locked>> | 86% | 46,209 psi | 72% | 3146 fps | 95.5% |
| IMR 7828 SSC | <<locked>> | 86% | 42,960 psi | 67% | 3179 fps | 95% |
| Lovex S065 | <<locked>> | 80% | 47,340 psi | 74% | 3153 fps | 99.5% |
| Lovex S070 | <<locked>> | 80% | 45,672 psi | 72% | 3140 fps | 98.6% |
| Lovex S071 | <<locked>> | 84% | 33,431 psi | 52% | 2851 fps | 95.9% |
| Norma 204 | <<locked>> | 80% | 43,816 psi | 69% | 3133 fps | 96.4% |
| Norma 217 | <<locked>> | 98% | 37,043 psi | 58% | 3084 fps | 95.8% |
| Norma MRP | 58.8 gr | 80% | 35,476 psi | 56% | 3009 fps | 95.3% |
| Norma URP | <<locked>> | 80% | 44,788 psi | 70% | 3163 fps | 99.7% |
| Ramshot Grand | <<locked>> | 84% | 41,843 psi | 66% | 3163 fps | 95% |
| Ramshot Hunter | <<locked>> | 80% | 43,656 psi | 68% | 3150 fps | 98.7% |
| Ramshot Magnum | <<locked>> | 84% | 36,550 psi | 57% | 2995 fps | 95.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,311 psi | 44% | 1991 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 45,716 psi | 72% | 3192 fps | 99.7% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 43,976 psi | 69% | 3212 fps | 99.6% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 35,810 psi | 56% | 3054 fps | 95.7% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 46,717 psi | 73% | 3301 fps | 95.3% |
| Rottweil R 903 | <<locked>> | 80% | 52,678 psi | 83% | 3255 fps | 100% |
| Rottweil R 904 | <<locked>> | 84% | 45,049 psi | 71% | 3133 fps | 95.8% |
| Rottweil R 905 | <<locked>> | 82% | 40,118 psi | 63% | 3064 fps | 95.6% |
| Rottweil R 907 | <<locked>> | 80% | 48,428 psi | 76% | 3182 fps | 98.5% |
| Shooters World Long Rifle | <<locked>> | 80% | 47,340 psi | 74% | 3153 fps | 99.5% |
| Shooters World SW4350 | <<locked>> | 80% | 45,672 psi | 72% | 3140 fps | 98.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 52,475 psi | 82% | 3120 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 46,253 psi | 72% | 3087 fps | 98.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 39,769 psi | 62% | 3058 fps | 95.5% |
| Somchem S355 | <<locked>> | 80% | 52,475 psi | 82% | 3251 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 46,180 psi | 72% | 3117 fps | 95.3% |
| Somchem S365 | <<locked>> | 80% | 41,785 psi | 65% | 3110 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 38,000 psi | 60% | 2976 fps | 95.8% |
| Unknown powder | <<locked>> | 80% | 47,921 psi | 75% | 3222 fps | 99.8% |
| Vihtavuori N150 | <<locked>> | 80% | 45,049 psi | 71% | 3071 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 48,211 psi | 76% | 3189 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 86% | 39,131 psi | 61% | 2992 fps | 95.9% |
| Vihtavuori N550 | <<locked>> | 80% | 48,718 psi | 76% | 3238 fps | 99.9% |
| Vihtavuori N555 | <<locked>> | 80% | 36,651 psi | 57% | 2992 fps | 98.9% |
| Vihtavuori N560 | 63.4 gr | 88% | 45,005 psi | 71% | 3235 fps | 95.1% |
| Vihtavuori N565 | <<locked>> | 92% | 44,425 psi | 70% | 3196 fps | 95.3% |
| Vihtavuori N568 | <<locked>> | 98% | 48,066 psi | 75% | 3320 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 45,498 psi | 71% | 3107 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 51,372 psi | 81% | 3307 fps | 99.3% |
| Winchester StaBALL HD | 58.2 gr | 80% | 29,037 psi | 46% | 2900 fps | 98.9% |
| Winchester Supreme 780 | <<locked>> | 82% | 40,654 psi | 64% | 3038 fps | 95.7% |
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 78 powders for .257 Weath. Mag. loaded with the .257 | 100gr | Hasler Hunting. Hodgdon Retumbo delivers the highest muzzle velocity at 3,530 fps; across all powders the maximum-charge window runs from 2,172 fps to 3,530 fps. ADI AR 2217 gives the best case fill at 100 %, and 78 of the 78 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 100.0 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. Winchester StaBALL HD, Vihtavuori N560, Norma MRP rank at the top here: for .257 Weath. Mag. with the .257 | 100gr | Hasler Hunting 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.