Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 100gr | Barnes TTSX 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 IMR 7828 SSC.
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% | 57,696 psi | 90% | 3366 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 55,114 psi | 86% | 3353 fps | 100% |
| Accurate High Country | <<locked>> | 92% | 55,550 psi | 87% | 3468 fps | 98.3% |
| Accurate MAGPRO | <<locked>> | 94% | 56,768 psi | 89% | 3474 fps | 97.5% |
| ADI AR 2208 | <<locked>> | 82% | 56,144 psi | 88% | 3320 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 56,202 psi | 88% | 3412 fps | 99.1% |
| ADI AR 2213 | <<locked>> | 94% | 54,041 psi | 85% | 3409 fps | 97.9% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 48,544 psi | 76% | 3284 fps | 97.1% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 43,091 psi | 68% | 3225 fps | 98.6% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 56,492 psi | 89% | 3412 fps | 99.1% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 56,492 psi | 89% | 3412 fps | 99.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 57,522 psi | 90% | 3346 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 88% | 56,057 psi | 88% | 3422 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 57,377 psi | 90% | 3435 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 55,782 psi | 87% | 3399 fps | 99% |
| Alliant Reloder-22 | <<locked>> | 94% | 53,940 psi | 85% | 3402 fps | 98.9% |
| Alliant Reloder-23 | <<locked>> | 96% | 55,317 psi | 87% | 3383 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 54,781 psi | 86% | 3445 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 55,854 psi | 88% | 3478 fps | 100% |
| Bofors RP15 | <<locked>> | 98% | 56,855 psi | 89% | 3451 fps | 99.2% |
| Bofors RP30ᴾ | <<locked>> | 100% | 50,705 psi | 79% | 3363 fps | 97.9% |
| Bofors RP5 | <<locked>> | 94% | 53,940 psi | 85% | 3402 fps | 98.9% |
| Bofors RP7 | <<locked>> | 86% | 57,493 psi | 90% | 3356 fps | 99.6% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 53,838 psi | 84% | 3392 fps | 98.7% |
| Hodgdon H414 | <<locked>> | 86% | 56,927 psi | 89% | 3415 fps | 99.8% |
| Hodgdon H4350 | <<locked>> | 84% | 56,028 psi | 88% | 3369 fps | 99.2% |
| Hodgdon H4831 | <<locked>> | 92% | 53,954 psi | 85% | 3340 fps | 97.2% |
| Hodgdon H4831 SC | <<locked>> | 94% | 56,623 psi | 89% | 3386 fps | 97.7% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 56,376 psi | 88% | 3330 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 53,461 psi | 84% | 3514 fps | 99.6% |
| Hodgdon Superformance | <<locked>> | 84% | 53,809 psi | 84% | 3383 fps | 99.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,709 psi | 58% | 2169 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 55,695 psi | 87% | 3337 fps | 99.5% |
| IMR 4451 Enduron | <<locked>> | 84% | 55,521 psi | 87% | 3327 fps | 99.7% |
| IMR 4831 | <<locked>> | 88% | 55,637 psi | 87% | 3346 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 54,998 psi | 86% | 3327 fps | 97.6% |
| IMR 7828 SSC | <<locked>> | 96% | 55,680 psi | 87% | 3451 fps | 98.3% |
| Lovex S065 | <<locked>> | 86% | 55,970 psi | 88% | 3320 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 54,244 psi | 85% | 3314 fps | 99.7% |
| Lovex S071ᴾ | <<locked>> | 100% | 54,897 psi | 86% | 3320 fps | 99.9% |
| Norma 204 | <<locked>> | 88% | 56,971 psi | 89% | 3399 fps | 99% |
| Norma 217ᴾ | <<locked>> | 100% | 38,566 psi | 60% | 3130 fps | 96.5% |
| Norma MRP | <<locked>> | 92% | 53,795 psi | 84% | 3425 fps | 99.6% |
| Norma URP | <<locked>> | 88% | 57,319 psi | 90% | 3396 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 56,666 psi | 89% | 3474 fps | 98.8% |
| Ramshot Hunter | <<locked>> | 88% | 56,347 psi | 88% | 3399 fps | 100% |
| Ramshot Magnum | <<locked>> | 98% | 55,129 psi | 86% | 3396 fps | 99.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,536 psi | 59% | 2218 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 57,101 psi | 89% | 3425 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 55,390 psi | 87% | 3379 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 53,679 psi | 84% | 3406 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 54,578 psi | 86% | 3507 fps | 100% |
| Rottweil R 903 | <<locked>> | 82% | 55,042 psi | 86% | 3301 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 57,522 psi | 90% | 3383 fps | 98.5% |
| Rottweil R 905 | <<locked>> | 92% | 55,172 psi | 86% | 3386 fps | 99.1% |
| Rottweil R 907 | <<locked>> | 86% | 57,493 psi | 90% | 3356 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 86% | 55,970 psi | 88% | 3320 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 54,244 psi | 85% | 3314 fps | 99.7% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 56,855 psi | 89% | 3366 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 55,201 psi | 87% | 3166 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 55,463 psi | 87% | 3268 fps | 99.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 54,737 psi | 86% | 3379 fps | 99% |
| Somchem S355 | <<locked>> | 82% | 54,882 psi | 86% | 3297 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 55,419 psi | 87% | 3301 fps | 97.5% |
| Somchem S365 | <<locked>> | 88% | 53,925 psi | 85% | 3337 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 55,680 psi | 87% | 3353 fps | 99.5% |
| Vihtavuori N150 | <<locked>> | 84% | 56,188 psi | 88% | 3264 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 55,579 psi | 87% | 3330 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 55,332 psi | 87% | 3327 fps | 99.3% |
| Vihtavuori N550 | <<locked>> | 86% | 54,737 psi | 86% | 3333 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 57,203 psi | 90% | 3412 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 57,711 psi | 90% | 3491 fps | 98.2% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 57,580 psi | 90% | 3461 fps | 98.4% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 55,332 psi | 87% | 3278 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 57,188 psi | 90% | 3415 fps | 99.8% |
| Winchester StaBALL HD | <<locked>> | 98% | 57,246 psi | 90% | 3530 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 55,811 psi | 87% | 3346 fps | 99% |
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% | 32,779 psi | 51% | 2838 fps | 95.6% |
| Accurate 4350 | <<locked>> | 80% | 44,396 psi | 70% | 3153 fps | 99.7% |
| Accurate High Country | <<locked>> | 86% | 44,759 psi | 70% | 3245 fps | 95.8% |
| Accurate MAGPRO | <<locked>> | 90% | 48,994 psi | 77% | 3320 fps | 95.7% |
| ADI AR 2208 | <<locked>> | 80% | 52,605 psi | 82% | 3258 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 39,842 psi | 62% | 3068 fps | 95.3% |
| ADI AR 2213 | <<locked>> | 88% | 43,729 psi | 69% | 3189 fps | 95.2% |
| ADI AR 2217 | <<locked>> | 96% | 42,206 psi | 66% | 3136 fps | 95% |
| ADI AR 2225 | <<locked>> | 94% | 35,230 psi | 55% | 3005 fps | 95.7% |
| Alliant Power Pro Varmint | <<locked>> | 82% | 40,190 psi | 63% | 3071 fps | 95.4% |
| Alliant Power Pro Varmint | <<locked>> | 82% | 40,190 psi | 63% | 3071 fps | 95.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 53,896 psi | 84% | 3287 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 42,656 psi | 67% | 3166 fps | 99.8% |
| Alliant Reloder-17 | <<locked>> | 80% | 49,719 psi | 78% | 3307 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 39,798 psi | 62% | 3061 fps | 95.3% |
| Alliant Reloder-22 | <<locked>> | 86% | 40,814 psi | 64% | 3123 fps | 95.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 31,633 psi | 50% | 2877 fps | 98.6% |
| Alliant Reloder-25 | <<locked>> | 84% | 31,517 psi | 49% | 2890 fps | 95.7% |
| Alliant Reloder-26 | <<locked>> | 80% | 34,795 psi | 55% | 3025 fps | 97.8% |
| Bofors RP15 | <<locked>> | 88% | 40,437 psi | 63% | 3110 fps | 95.5% |
| Bofors RP30 | <<locked>> | 94% | 40,785 psi | 64% | 3143 fps | 95% |
| Bofors RP5 | <<locked>> | 86% | 40,814 psi | 64% | 3123 fps | 95.8% |
| Bofors RP7 | <<locked>> | 80% | 47,485 psi | 74% | 3166 fps | 98.4% |
| Hodgdon H1000 | <<locked>> | 92% | 40,263 psi | 63% | 3094 fps | 95% |
| Hodgdon H414 | <<locked>> | 80% | 46,412 psi | 73% | 3212 fps | 98.6% |
| Hodgdon H4350 | <<locked>> | 80% | 48,936 psi | 77% | 3235 fps | 98.1% |
| Hodgdon H4831 | <<locked>> | 88% | 47,065 psi | 74% | 3202 fps | 95.5% |
| Hodgdon H4831 SC | <<locked>> | 88% | 45,919 psi | 72% | 3179 fps | 95.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 40,263 psi | 63% | 3035 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 90% | 37,782 psi | 59% | 3130 fps | 95.3% |
| Hodgdon Superformance | <<locked>> | 80% | 46,224 psi | 72% | 3235 fps | 98.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,528 psi | 43% | 1946 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 42,946 psi | 67% | 3081 fps | 97.4% |
| IMR 4451 Enduron | <<locked>> | 80% | 48,820 psi | 77% | 3199 fps | 98.9% |
| IMR 4831 | <<locked>> | 80% | 42,279 psi | 66% | 3091 fps | 99.5% |
| IMR 4955 Enduron | <<locked>> | 86% | 45,324 psi | 71% | 3133 fps | 95.3% |
| IMR 7828 SSC | 64 gr | 90% | 45,165 psi | 71% | 3235 fps | 95.8% |
| Lovex S065 | <<locked>> | 80% | 46,311 psi | 73% | 3140 fps | 99.4% |
| Lovex S070 | <<locked>> | 80% | 44,585 psi | 70% | 3120 fps | 98.4% |
| Lovex S071 | <<locked>> | 84% | 32,097 psi | 50% | 2818 fps | 95.3% |
| Norma 204 | <<locked>> | 80% | 43,076 psi | 68% | 3120 fps | 96.2% |
| Norma 217 | <<locked>> | 98% | 35,926 psi | 56% | 3054 fps | 95.3% |
| Norma MRP | 60.5 gr | 82% | 37,086 psi | 58% | 3054 fps | 96% |
| Norma URP | <<locked>> | 80% | 43,801 psi | 69% | 3143 fps | 99.6% |
| Ramshot Grand | <<locked>> | 88% | 41,771 psi | 65% | 3163 fps | 95% |
| Ramshot Hunter | <<locked>> | 80% | 42,844 psi | 67% | 3133 fps | 98.6% |
| Ramshot Magnum | <<locked>> | 88% | 37,289 psi | 58% | 3018 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,949 psi | 44% | 1988 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 52,953 psi | 83% | 3360 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 44,541 psi | 70% | 3173 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 42,975 psi | 67% | 3192 fps | 99.5% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 34,679 psi | 54% | 3022 fps | 95.1% |
| Rottweil R 903 | <<locked>> | 80% | 51,488 psi | 81% | 3241 fps | 100% |
| Rottweil R 904 | <<locked>> | 84% | 44,106 psi | 69% | 3117 fps | 95.5% |
| Rottweil R 905 | <<locked>> | 82% | 39,073 psi | 61% | 3041 fps | 95.3% |
| Rottweil R 907 | <<locked>> | 80% | 47,485 psi | 74% | 3166 fps | 98.4% |
| Shooters World Long Rifle | <<locked>> | 80% | 46,311 psi | 73% | 3140 fps | 99.4% |
| Shooters World SW4350 | <<locked>> | 80% | 44,585 psi | 70% | 3120 fps | 98.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 53,272 psi | 83% | 3307 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 51,663 psi | 81% | 3110 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 45,252 psi | 71% | 3074 fps | 98.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 38,740 psi | 61% | 3038 fps | 95.1% |
| Somchem S355 | <<locked>> | 80% | 51,416 psi | 81% | 3238 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 45,150 psi | 71% | 3097 fps | 95% |
| Somchem S365 | <<locked>> | 80% | 40,640 psi | 64% | 3091 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 36,912 psi | 58% | 2953 fps | 95.4% |
| Vihtavuori N150 | <<locked>> | 80% | 49,240 psi | 77% | 3150 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 45,208 psi | 71% | 3140 fps | 99.8% |
| Vihtavuori N165 | <<locked>> | 84% | 36,622 psi | 57% | 2936 fps | 95% |
| Vihtavuori N550 | <<locked>> | 80% | 44,556 psi | 70% | 3140 fps | 99.6% |
| Vihtavuori N555 | <<locked>> | 80% | 35,418 psi | 56% | 2966 fps | 98.6% |
| Vihtavuori N560 | <<locked>> | 88% | 46,601 psi | 73% | 3271 fps | 95.6% |
| Vihtavuori N565 | <<locked>> | 92% | 43,352 psi | 68% | 3176 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 44,556 psi | 70% | 3094 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 46,412 psi | 73% | 3212 fps | 98.6% |
| Winchester StaBALL HD | 58.5 gr | 80% | 28,050 psi | 44% | 2867 fps | 98.4% |
| Winchester Supreme 780 | <<locked>> | 84% | 39,015 psi | 61% | 3002 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 | 100gr | Barnes TTSX BT. Winchester StaBALL HD delivers the highest muzzle velocity at 3,530 fps; across all powders the maximum-charge window runs from 2,169 fps to 3,530 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 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, Norma MRP, IMR 7828 SSC rank at the top here: for .257 Weath. Mag. with the .257 | 100gr | Barnes TTSX 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.