Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 101gr | Barnes LRX BT bullet and 77 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Winchester StaBALL HD, 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>> | 94% | 55,622 psi | 87% | 3317 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 56,753 psi | 89% | 3363 fps | 100% |
| Accurate High Country | <<locked>> | 92% | 57,116 psi | 90% | 3484 fps | 98.7% |
| Accurate MAGPRO | <<locked>> | 92% | 54,302 psi | 85% | 3412 fps | 97.1% |
| ADI AR 2208 | <<locked>> | 82% | 57,145 psi | 90% | 3317 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 57,435 psi | 90% | 3419 fps | 99.2% |
| ADI AR 2213 | <<locked>> | 94% | 55,332 psi | 87% | 3419 fps | 98.2% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 49,908 psi | 78% | 3297 fps | 97.5% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 44,483 psi | 70% | 3245 fps | 99% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 57,609 psi | 90% | 3412 fps | 99.3% |
| Alliant Power Pro Varmint | <<locked>> | 90% | 54,128 psi | 85% | 3350 fps | 98.8% |
| Alliant Reloder-16 | <<locked>> | 88% | 57,522 psi | 90% | 3425 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 54,868 psi | 86% | 3376 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 57,058 psi | 89% | 3406 fps | 99.2% |
| Alliant Reloder-22 | <<locked>> | 94% | 55,419 psi | 87% | 3412 fps | 99.2% |
| Alliant Reloder-23 | <<locked>> | 96% | 56,536 psi | 89% | 3386 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 56,014 psi | 88% | 3448 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 57,334 psi | 90% | 3484 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 96% | 57,363 psi | 90% | 3369 fps | 95.9% |
| Bofors RP15 | <<locked>> | 96% | 54,607 psi | 86% | 3399 fps | 99% |
| Bofors RP30ᴾ | <<locked>> | 100% | 52,098 psi | 82% | 3376 fps | 98.2% |
| Bofors RP5 | <<locked>> | 94% | 55,419 psi | 87% | 3412 fps | 99.2% |
| Bofors RP7 | <<locked>> | 84% | 55,303 psi | 87% | 3304 fps | 99.5% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 55,013 psi | 86% | 3399 fps | 99% |
| Hodgdon H414 | <<locked>> | 84% | 54,578 psi | 86% | 3356 fps | 99.7% |
| Hodgdon H4350 | <<locked>> | 84% | 57,116 psi | 90% | 3373 fps | 99.3% |
| Hodgdon H4831 | <<locked>> | 92% | 55,216 psi | 87% | 3346 fps | 97.6% |
| Hodgdon H4831 SC | <<locked>> | 92% | 54,172 psi | 85% | 3327 fps | 97.4% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 57,725 psi | 90% | 3333 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 54,998 psi | 86% | 3527 fps | 99.8% |
| Hodgdon Superformance | <<locked>> | 84% | 55,172 psi | 86% | 3392 fps | 99.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,927 psi | 58% | 2159 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 56,840 psi | 89% | 3340 fps | 99.6% |
| IMR 4451 Enduron | <<locked>> | 84% | 56,507 psi | 89% | 3327 fps | 99.8% |
| IMR 4831 | <<locked>> | 88% | 57,000 psi | 89% | 3350 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 56,144 psi | 88% | 3330 fps | 97.9% |
| IMR 7828 SSC | <<locked>> | 96% | 57,087 psi | 89% | 3461 fps | 98.6% |
| Lovex S065 | <<locked>> | 86% | 57,217 psi | 90% | 3323 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 55,535 psi | 87% | 3317 fps | 99.8% |
| Lovex S071ᴾ | <<locked>> | 100% | 56,695 psi | 89% | 3333 fps | 100% |
| Norma 204 | <<locked>> | 86% | 54,215 psi | 85% | 3337 fps | 98.7% |
| Norma 217ᴾ | <<locked>> | 100% | 39,929 psi | 63% | 3153 fps | 97.1% |
| Norma MRP | <<locked>> | 92% | 55,332 psi | 87% | 3438 fps | 99.8% |
| Norma URP | <<locked>> | 86% | 54,940 psi | 86% | 3340 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 53,911 psi | 84% | 3412 fps | 98.4% |
| Ramshot Hunter | <<locked>> | 88% | 57,667 psi | 90% | 3406 fps | 100% |
| Ramshot Magnum | <<locked>> | 98% | 56,521 psi | 89% | 3406 fps | 99.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,811 psi | 59% | 2211 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 56,869 psi | 89% | 3383 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 55,056 psi | 86% | 3412 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 56,246 psi | 88% | 3527 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 51,082 psi | 80% | 3383 fps | 96.7% |
| Rottweil R 903 | <<locked>> | 82% | 56,492 psi | 89% | 3307 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 55,042 psi | 86% | 3323 fps | 98.1% |
| Rottweil R 905 | <<locked>> | 92% | 56,550 psi | 89% | 3396 fps | 99.3% |
| Rottweil R 907 | <<locked>> | 84% | 55,303 psi | 87% | 3304 fps | 99.5% |
| Shooters World Long Rifle | <<locked>> | 86% | 57,217 psi | 90% | 3323 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 55,535 psi | 87% | 3317 fps | 99.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 56,202 psi | 88% | 3163 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 56,739 psi | 89% | 3271 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 56,101 psi | 88% | 3389 fps | 99.2% |
| Somchem S355 | <<locked>> | 82% | 56,159 psi | 88% | 3301 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 56,724 psi | 89% | 3307 fps | 97.8% |
| Somchem S365 | <<locked>> | 88% | 55,376 psi | 87% | 3340 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 57,130 psi | 90% | 3360 fps | 99.7% |
| Vihtavuori N150 | <<locked>> | 84% | 57,435 psi | 90% | 3264 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 56,855 psi | 89% | 3333 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 56,753 psi | 89% | 3333 fps | 99.5% |
| Vihtavuori N550 | <<locked>> | 86% | 56,043 psi | 88% | 3337 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 55,114 psi | 86% | 3363 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 55,143 psi | 86% | 3428 fps | 97.8% |
| Vihtavuori N565 | <<locked>> | 98% | 55,245 psi | 87% | 3406 fps | 98.1% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 52,141 psi | 82% | 3392 fps | 96.3% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 56,594 psi | 89% | 3281 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 54,810 psi | 86% | 3360 fps | 99.7% |
| Winchester StaBALL HD | <<locked>> | 96% | 54,563 psi | 86% | 3474 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 57,232 psi | 90% | 3356 fps | 99.2% |
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>> | 80% | 34,272 psi | 54% | 2864 fps | 96.3% |
| Accurate 4350 | <<locked>> | 80% | 45,905 psi | 72% | 3169 fps | 99.9% |
| Accurate High Country | <<locked>> | 84% | 42,902 psi | 67% | 3189 fps | 95.3% |
| Accurate MAGPRO | <<locked>> | 88% | 46,992 psi | 74% | 3261 fps | 95.2% |
| ADI AR 2208 | <<locked>> | 80% | 53,809 psi | 84% | 3261 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 40,959 psi | 64% | 3081 fps | 95.8% |
| ADI AR 2213 | <<locked>> | 88% | 44,904 psi | 70% | 3202 fps | 95.7% |
| ADI AR 2217 | <<locked>> | 96% | 43,511 psi | 68% | 3153 fps | 95.6% |
| ADI AR 2225 | <<locked>> | 92% | 34,069 psi | 53% | 2956 fps | 95.1% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 38,711 psi | 61% | 3015 fps | 95% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 38,638 psi | 61% | 3015 fps | 95% |
| Alliant Reloder-16 | <<locked>> | 80% | 43,976 psi | 69% | 3179 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 51,039 psi | 80% | 3314 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 40,915 psi | 64% | 3071 fps | 95.8% |
| Alliant Reloder-22 | <<locked>> | 84% | 39,320 psi | 62% | 3071 fps | 95.4% |
| Alliant Reloder-23 | <<locked>> | 80% | 32,866 psi | 52% | 2900 fps | 99.1% |
| Alliant Reloder-25 | <<locked>> | 82% | 30,603 psi | 48% | 2848 fps | 95.3% |
| Alliant Reloder-26 | <<locked>> | 80% | 36,216 psi | 57% | 3051 fps | 98.4% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 53,824 psi | 84% | 3301 fps | 95% |
| Bofors RP15 | <<locked>> | 86% | 39,030 psi | 61% | 3061 fps | 95.2% |
| Bofors RP30 | <<locked>> | 94% | 42,308 psi | 66% | 3166 fps | 95.7% |
| Bofors RP5 | <<locked>> | 84% | 39,320 psi | 62% | 3071 fps | 95.4% |
| Bofors RP7 | <<locked>> | 80% | 48,617 psi | 76% | 3173 fps | 98.6% |
| Hodgdon H1000 | <<locked>> | 92% | 41,510 psi | 65% | 3110 fps | 95.6% |
| Hodgdon H414 | <<locked>> | 80% | 47,616 psi | 75% | 3222 fps | 98.9% |
| Hodgdon H4350 | <<locked>> | 80% | 49,995 psi | 78% | 3238 fps | 98.4% |
| Hodgdon H4831 | <<locked>> | 86% | 44,889 psi | 70% | 3143 fps | 95% |
| Hodgdon H4831 SC | <<locked>> | 88% | 47,108 psi | 74% | 3192 fps | 95.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 41,437 psi | 65% | 3045 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 39,059 psi | 61% | 3153 fps | 96% |
| Hodgdon Superformance | <<locked>> | 80% | 47,514 psi | 74% | 3245 fps | 98.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,702 psi | 43% | 1936 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 43,990 psi | 69% | 3091 fps | 97.8% |
| IMR 4451 Enduron | <<locked>> | 80% | 50,024 psi | 78% | 3205 fps | 99.1% |
| IMR 4831 | <<locked>> | 80% | 43,787 psi | 69% | 3107 fps | 99.7% |
| IMR 4955 Enduron | <<locked>> | 86% | 46,383 psi | 73% | 3140 fps | 95.7% |
| IMR 7828 SSC | <<locked>> | 88% | 43,178 psi | 68% | 3173 fps | 95.2% |
| Lovex S065 | <<locked>> | 80% | 47,514 psi | 74% | 3146 fps | 99.5% |
| Lovex S070 | <<locked>> | 80% | 45,818 psi | 72% | 3130 fps | 98.7% |
| Lovex S071 | <<locked>> | 82% | 31,502 psi | 49% | 2785 fps | 95.1% |
| Norma 204 | <<locked>> | 80% | 44,222 psi | 69% | 3130 fps | 96.6% |
| Norma 217 | <<locked>> | 96% | 34,969 psi | 55% | 3015 fps | 95% |
| Norma MRP | 58.8 gr | 80% | 35,839 psi | 56% | 3009 fps | 95.6% |
| Norma URP | <<locked>> | 80% | 45,005 psi | 71% | 3153 fps | 99.8% |
| Ramshot Grand | <<locked>> | 88% | 43,105 psi | 68% | 3182 fps | 95.6% |
| Ramshot Hunter | <<locked>> | 80% | 44,063 psi | 69% | 3146 fps | 98.9% |
| Ramshot Magnum | <<locked>> | 86% | 35,882 psi | 56% | 2966 fps | 95.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,181 psi | 44% | 1978 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 45,948 psi | 72% | 3189 fps | 99.8% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 44,208 psi | 69% | 3202 fps | 99.6% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 36,042 psi | 56% | 3054 fps | 96% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 47,311 psi | 74% | 3304 fps | 95.6% |
| Rottweil R 903 | <<locked>> | 80% | 52,910 psi | 83% | 3248 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 42,308 psi | 66% | 3058 fps | 95% |
| Rottweil R 905 | <<locked>> | 82% | 40,306 psi | 63% | 3058 fps | 95.8% |
| Rottweil R 907 | <<locked>> | 80% | 48,617 psi | 76% | 3173 fps | 98.6% |
| Shooters World Long Rifle | <<locked>> | 80% | 47,514 psi | 74% | 3146 fps | 99.5% |
| Shooters World SW4350 | <<locked>> | 80% | 45,818 psi | 72% | 3130 fps | 98.7% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 52,881 psi | 83% | 3114 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 46,659 psi | 73% | 3087 fps | 98.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 39,958 psi | 63% | 3051 fps | 95.7% |
| Somchem S355 | <<locked>> | 80% | 52,634 psi | 82% | 3241 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 46,340 psi | 73% | 3107 fps | 95.5% |
| Somchem S365 | <<locked>> | 80% | 41,974 psi | 66% | 3100 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 38,189 psi | 60% | 2972 fps | 96% |
| Vihtavuori N150 | <<locked>> | 80% | 50,430 psi | 79% | 3153 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 46,398 psi | 73% | 3146 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 84% | 38,029 psi | 60% | 2956 fps | 95.6% |
| Vihtavuori N550 | <<locked>> | 80% | 46,021 psi | 72% | 3153 fps | 99.8% |
| Vihtavuori N555 | <<locked>> | 80% | 36,854 psi | 58% | 2986 fps | 99% |
| Vihtavuori N560 | 63.2 gr | 86% | 44,599 psi | 70% | 3212 fps | 95.1% |
| Vihtavuori N565 | <<locked>> | 92% | 44,715 psi | 70% | 3192 fps | 95.5% |
| Vihtavuori N568 | <<locked>> | 98% | 48,385 psi | 76% | 3314 fps | 95.2% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 45,687 psi | 72% | 3100 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 47,848 psi | 75% | 3225 fps | 98.9% |
| Winchester StaBALL HD | 58.2 gr | 80% | 29,327 psi | 46% | 2904 fps | 99.1% |
| Winchester Supreme 780 | <<locked>> | 84% | 40,263 psi | 63% | 3018 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 77 powders for .257 Weath. Mag. loaded with the .257 | 101gr | Barnes LRX BT. Hodgdon Retumbo delivers the highest muzzle velocity at 3,527 fps; across all powders the maximum-charge window runs from 2,159 fps to 3,527 fps. ADI AR 2217 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 101.0 gr projectile in 0.257" calls for a 1:9.0 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, Norma MRP, Vihtavuori N560 rank at the top here: for .257 Weath. Mag. with the .257 | 101gr | Barnes LRX BT 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.