Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 100gr | Barnes TSX BT bullet and 76 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 3100 | <<locked>> | 94% | 54,781 psi | 86% | 3320 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 55,608 psi | 87% | 3363 fps | 100% |
| Accurate High Country | <<locked>> | 92% | 56,492 psi | 89% | 3488 fps | 98.5% |
| Accurate MAGPRO | <<locked>> | 94% | 57,667 psi | 90% | 3491 fps | 97.7% |
| ADI AR 2208 | <<locked>> | 82% | 56,608 psi | 89% | 3327 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 57,145 psi | 90% | 3432 fps | 99.2% |
| ADI AR 2213 | <<locked>> | 94% | 54,911 psi | 86% | 3425 fps | 98.1% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 49,298 psi | 77% | 3301 fps | 97.3% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 43,743 psi | 69% | 3241 fps | 98.9% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 57,159 psi | 90% | 3422 fps | 99.2% |
| Alliant Reloder-16 | <<locked>> | 88% | 56,826 psi | 89% | 3432 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 54,085 psi | 85% | 3383 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 56,449 psi | 88% | 3412 fps | 99.2% |
| Alliant Reloder-22 | <<locked>> | 94% | 54,853 psi | 86% | 3422 fps | 99.1% |
| Alliant Reloder-23 | <<locked>> | 96% | 56,014 psi | 88% | 3396 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 55,724 psi | 87% | 3458 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 56,869 psi | 89% | 3491 fps | 100% |
| Bofors RP15 | <<locked>> | 96% | 53,766 psi | 84% | 3396 fps | 98.8% |
| Bofors RP30ᴾ | <<locked>> | 100% | 51,372 psi | 81% | 3376 fps | 98% |
| Bofors RP5 | <<locked>> | 94% | 54,853 psi | 86% | 3422 fps | 99.1% |
| Bofors RP7 | <<locked>> | 84% | 54,578 psi | 86% | 3307 fps | 99.4% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 54,360 psi | 85% | 3402 fps | 98.9% |
| Hodgdon H414 | <<locked>> | 86% | 57,638 psi | 90% | 3425 fps | 99.9% |
| Hodgdon H4350 | <<locked>> | 84% | 56,710 psi | 89% | 3383 fps | 99.3% |
| Hodgdon H4831 | <<locked>> | 92% | 54,810 psi | 86% | 3356 fps | 97.5% |
| Hodgdon H4831 SC | <<locked>> | 94% | 57,537 psi | 90% | 3406 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 57,145 psi | 90% | 3343 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 54,346 psi | 85% | 3527 fps | 99.7% |
| Hodgdon Superformance | <<locked>> | 84% | 54,462 psi | 85% | 3396 fps | 99.6% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,825 psi | 58% | 2175 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 56,362 psi | 88% | 3350 fps | 99.6% |
| IMR 4451 Enduron | <<locked>> | 84% | 56,188 psi | 88% | 3337 fps | 99.7% |
| IMR 4831 | <<locked>> | 88% | 56,318 psi | 88% | 3360 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 55,825 psi | 87% | 3346 fps | 97.8% |
| IMR 7828 SSC | <<locked>> | 96% | 56,594 psi | 89% | 3468 fps | 98.5% |
| Lovex S065 | <<locked>> | 86% | 56,666 psi | 89% | 3333 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 54,911 psi | 86% | 3327 fps | 99.8% |
| Lovex S071ᴾ | <<locked>> | 100% | 55,883 psi | 88% | 3337 fps | 100% |
| Norma 204 | <<locked>> | 88% | 57,609 psi | 90% | 3412 fps | 99.2% |
| Norma 217ᴾ | <<locked>> | 100% | 39,291 psi | 62% | 3150 fps | 96.9% |
| Norma MRP | <<locked>> | 92% | 54,737 psi | 86% | 3445 fps | 99.7% |
| Norma URP | <<locked>> | 86% | 54,389 psi | 85% | 3350 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 57,624 psi | 90% | 3491 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 88% | 57,029 psi | 89% | 3412 fps | 100% |
| Ramshot Magnum | <<locked>> | 98% | 56,028 psi | 88% | 3412 fps | 99.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,652 psi | 59% | 2224 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 57,682 psi | 90% | 3432 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 56,101 psi | 88% | 3389 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 54,418 psi | 85% | 3419 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 55,651 psi | 87% | 3530 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 50,372 psi | 79% | 3379 fps | 96.4% |
| Rottweil R 903 | <<locked>> | 82% | 55,579 psi | 87% | 3310 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 54,491 psi | 85% | 3330 fps | 98% |
| Rottweil R 905 | <<locked>> | 92% | 55,840 psi | 88% | 3399 fps | 99.2% |
| Rottweil R 907 | <<locked>> | 84% | 54,578 psi | 86% | 3307 fps | 99.4% |
| Shooters World Long Rifle | <<locked>> | 86% | 56,666 psi | 89% | 3333 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 54,911 psi | 86% | 3327 fps | 99.8% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 57,595 psi | 90% | 3379 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 55,709 psi | 87% | 3176 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 56,086 psi | 88% | 3278 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 55,405 psi | 87% | 3392 fps | 99.1% |
| Somchem S355 | <<locked>> | 82% | 55,376 psi | 87% | 3307 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 56,217 psi | 88% | 3314 fps | 97.7% |
| Somchem S365 | <<locked>> | 88% | 54,679 psi | 86% | 3350 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 56,275 psi | 88% | 3366 fps | 99.6% |
| Vihtavuori N150 | <<locked>> | 84% | 56,666 psi | 89% | 3271 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 56,043 psi | 88% | 3337 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 56,202 psi | 88% | 3343 fps | 99.5% |
| Vihtavuori N550 | <<locked>> | 86% | 55,419 psi | 87% | 3343 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 54,215 psi | 85% | 3363 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 54,592 psi | 86% | 3438 fps | 97.7% |
| Vihtavuori N565 | <<locked>> | 98% | 54,375 psi | 85% | 3402 fps | 97.9% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 55,927 psi | 88% | 3291 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 53,998 psi | 85% | 3363 fps | 99.6% |
| Winchester StaBALL HD | <<locked>> | 96% | 53,853 psi | 84% | 3478 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 56,695 psi | 89% | 3363 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% | 33,199 psi | 52% | 2848 fps | 95.8% |
| Accurate 4350 | <<locked>> | 80% | 44,933 psi | 70% | 3166 fps | 99.8% |
| Accurate High Country | <<locked>> | 84% | 42,177 psi | 66% | 3182 fps | 95% |
| Accurate MAGPRO | <<locked>> | 90% | 49,879 psi | 78% | 3340 fps | 96% |
| ADI AR 2208 | <<locked>> | 80% | 53,345 psi | 84% | 3274 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 40,277 psi | 63% | 3077 fps | 95.5% |
| ADI AR 2213 | <<locked>> | 88% | 44,309 psi | 69% | 3205 fps | 95.5% |
| ADI AR 2217 | <<locked>> | 96% | 42,714 psi | 67% | 3150 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 94% | 35,665 psi | 56% | 3022 fps | 96% |
| Alliant Power Pro Varmint | <<locked>> | 82% | 40,828 psi | 64% | 3084 fps | 95.7% |
| Alliant Reloder-16 | <<locked>> | 80% | 43,207 psi | 68% | 3176 fps | 99.8% |
| Alliant Reloder-17 | <<locked>> | 80% | 50,270 psi | 79% | 3317 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 40,437 psi | 63% | 3077 fps | 95.6% |
| Alliant Reloder-22 | <<locked>> | 84% | 38,667 psi | 61% | 3068 fps | 95.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 32,082 psi | 50% | 2890 fps | 98.8% |
| Alliant Reloder-25 | <<locked>> | 84% | 32,039 psi | 50% | 2910 fps | 96.1% |
| Alliant Reloder-26 | <<locked>> | 80% | 35,230 psi | 55% | 3035 fps | 98% |
| Bofors RP15 | <<locked>> | 88% | 41,075 psi | 64% | 3127 fps | 95.8% |
| Bofors RP30 | <<locked>> | 94% | 41,611 psi | 65% | 3163 fps | 95.4% |
| Bofors RP5 | <<locked>> | 84% | 38,667 psi | 61% | 3068 fps | 95.1% |
| Bofors RP7 | <<locked>> | 80% | 47,935 psi | 75% | 3179 fps | 98.5% |
| Hodgdon H1000 | <<locked>> | 92% | 40,973 psi | 64% | 3114 fps | 95.4% |
| Hodgdon H414 | <<locked>> | 80% | 46,891 psi | 73% | 3222 fps | 98.7% |
| Hodgdon H4350 | <<locked>> | 80% | 49,632 psi | 78% | 3251 fps | 98.3% |
| Hodgdon H4831 | <<locked>> | 88% | 47,674 psi | 75% | 3219 fps | 95.8% |
| Hodgdon H4831 SC | <<locked>> | 88% | 46,528 psi | 73% | 3192 fps | 95.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 40,756 psi | 64% | 3045 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 38,305 psi | 60% | 3146 fps | 95.6% |
| Hodgdon Superformance | <<locked>> | 80% | 46,891 psi | 73% | 3248 fps | 98.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,543 psi | 43% | 1952 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 43,395 psi | 68% | 3094 fps | 97.6% |
| IMR 4451 Enduron | <<locked>> | 80% | 49,487 psi | 78% | 3212 fps | 99% |
| IMR 4831 | <<locked>> | 80% | 42,946 psi | 67% | 3107 fps | 99.6% |
| IMR 4955 Enduron | <<locked>> | 86% | 45,876 psi | 72% | 3146 fps | 95.5% |
| IMR 7828 SSC | <<locked>> | 90% | 45,774 psi | 72% | 3251 fps | 96.1% |
| Lovex S065 | <<locked>> | 80% | 46,789 psi | 73% | 3150 fps | 99.5% |
| Lovex S070 | <<locked>> | 80% | 45,063 psi | 71% | 3133 fps | 98.5% |
| Lovex S071 | <<locked>> | 84% | 32,547 psi | 51% | 2831 fps | 95.5% |
| Norma 204 | <<locked>> | 80% | 43,511 psi | 68% | 3133 fps | 96.4% |
| Norma 217 | <<locked>> | 98% | 36,448 psi | 57% | 3068 fps | 95.7% |
| Norma MRP | 59.7 gr | 80% | 34,969 psi | 55% | 2995 fps | 95.1% |
| Norma URP | <<locked>> | 80% | 44,280 psi | 69% | 3153 fps | 99.7% |
| Ramshot Grand | <<locked>> | 88% | 42,598 psi | 67% | 3186 fps | 95.4% |
| Ramshot Hunter | <<locked>> | 80% | 43,265 psi | 68% | 3143 fps | 98.7% |
| Ramshot Magnum | <<locked>> | 88% | 37,971 psi | 60% | 3038 fps | 95.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,152 psi | 44% | 1998 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 53,519 psi | 84% | 3369 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 45,252 psi | 71% | 3189 fps | 99.7% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 43,627 psi | 68% | 3205 fps | 99.6% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 35,317 psi | 55% | 3045 fps | 95.6% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 46,615 psi | 73% | 3301 fps | 95.3% |
| Rottweil R 903 | <<locked>> | 80% | 52,025 psi | 82% | 3251 fps | 100% |
| Rottweil R 904 | <<locked>> | 84% | 44,730 psi | 70% | 3130 fps | 95.7% |
| Rottweil R 905 | <<locked>> | 82% | 39,508 psi | 62% | 3054 fps | 95.5% |
| Rottweil R 907 | <<locked>> | 80% | 47,935 psi | 75% | 3179 fps | 98.5% |
| Shooters World Long Rifle | <<locked>> | 80% | 46,789 psi | 73% | 3150 fps | 99.5% |
| Shooters World SW4350 | <<locked>> | 80% | 45,063 psi | 71% | 3133 fps | 98.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 53,751 psi | 84% | 3317 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 52,170 psi | 82% | 3123 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 45,905 psi | 72% | 3091 fps | 98.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 39,175 psi | 61% | 3048 fps | 95.3% |
| Somchem S355 | <<locked>> | 80% | 51,924 psi | 81% | 3248 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 45,687 psi | 72% | 3110 fps | 95.3% |
| Somchem S365 | <<locked>> | 80% | 41,191 psi | 65% | 3104 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 37,492 psi | 59% | 2969 fps | 95.7% |
| Vihtavuori N150 | <<locked>> | 80% | 49,705 psi | 78% | 3159 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 45,701 psi | 72% | 3150 fps | 99.8% |
| Vihtavuori N165 | <<locked>> | 84% | 37,202 psi | 58% | 2949 fps | 95.2% |
| Vihtavuori N550 | <<locked>> | 80% | 45,208 psi | 71% | 3153 fps | 99.7% |
| Vihtavuori N555 | <<locked>> | 80% | 35,897 psi | 56% | 2979 fps | 98.7% |
| Vihtavuori N560 | 65.7 gr | 88% | 47,224 psi | 74% | 3284 fps | 95.9% |
| Vihtavuori N565 | <<locked>> | 92% | 43,961 psi | 69% | 3189 fps | 95.2% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 45,165 psi | 71% | 3104 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 47,094 psi | 74% | 3228 fps | 98.8% |
| Winchester StaBALL HD | 59.1 gr | 80% | 28,413 psi | 45% | 2881 fps | 98.7% |
| Winchester Supreme 780 | <<locked>> | 84% | 39,610 psi | 62% | 3015 fps | 95.4% |
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 76 powders for .257 Weath. Mag. loaded with the .257 | 100gr | Barnes TSX BT. ReloadSwiss RS 76 delivers the highest muzzle velocity at 3,530 fps; across all powders the maximum-charge window runs from 2,175 fps to 3,530 fps. ADI AR 2217 gives the best case fill at 100 %, and 76 of the 76 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 1:10.0 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, Vihtavuori N560, Norma MRP rank at the top here: for .257 Weath. Mag. with the .257 | 100gr | Barnes TSX 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.