Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 115gr | Speer TBBC bullet and 70 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ReloadSwiss RS 76 and Winchester StaBALL HD.
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>> | 90% | 54,012 psi | 85% | 3117 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 54,563 psi | 86% | 3146 fps | 100% |
| Accurate MAGPRO | <<locked>> | 90% | 56,536 psi | 89% | 3284 fps | 98.6% |
| ADI AR 2209 | <<locked>> | 88% | 55,463 psi | 87% | 3212 fps | 99.7% |
| ADI AR 2213 | <<locked>> | 92% | 57,435 psi | 90% | 3284 fps | 99.4% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 55,608 psi | 87% | 3245 fps | 99.5% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 49,995 psi | 78% | 3202 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 84% | 55,680 psi | 87% | 3209 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 55,201 psi | 87% | 3202 fps | 99.7% |
| Alliant Reloder-22 | <<locked>> | 92% | 57,667 psi | 90% | 3278 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 92% | 55,477 psi | 87% | 3186 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 96% | 55,027 psi | 86% | 3248 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 88% | 55,956 psi | 88% | 3274 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 52,707 psi | 83% | 3261 fps | 96.3% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 54,795 psi | 86% | 3173 fps | 96.9% |
| Bofors RP15 | <<locked>> | 94% | 56,826 psi | 89% | 3264 fps | 99.8% |
| Bofors RP30 | <<locked>> | 98% | 54,940 psi | 86% | 3258 fps | 99.5% |
| Bofors RP5 | <<locked>> | 92% | 57,667 psi | 90% | 3278 fps | 99.9% |
| Bofors RP7 | <<locked>> | 82% | 56,333 psi | 88% | 3150 fps | 100% |
| Hodgdon H1000 | <<locked>> | 98% | 57,203 psi | 90% | 3271 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 82% | 55,970 psi | 88% | 3202 fps | 100% |
| Hodgdon H4831 | <<locked>> | 90% | 56,985 psi | 89% | 3215 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 90% | 55,898 psi | 88% | 3196 fps | 98.8% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 55,927 psi | 88% | 3123 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 54,085 psi | 85% | 3337 fps | 100% |
| Hodgdon Superformance | <<locked>> | 82% | 56,797 psi | 89% | 3241 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,362 psi | 59% | 2041 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 54,636 psi | 86% | 3133 fps | 99.9% |
| IMR 4451 Enduron | <<locked>> | 82% | 57,479 psi | 90% | 3169 fps | 100% |
| IMR 4831 | <<locked>> | 84% | 54,853 psi | 86% | 3136 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 90% | 57,464 psi | 90% | 3192 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 92% | 55,564 psi | 87% | 3261 fps | 99.3% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 45,542 psi | 71% | 3100 fps | 97.9% |
| Lovex S065 | <<locked>> | 82% | 55,071 psi | 86% | 3114 fps | 100% |
| Lovex S070 | <<locked>> | 84% | 56,884 psi | 89% | 3166 fps | 100% |
| Lovex S071 | <<locked>> | 96% | 55,332 psi | 87% | 3140 fps | 100% |
| Norma 204 | <<locked>> | 84% | 55,796 psi | 87% | 3192 fps | 99.6% |
| Norma 217ᴾ | <<locked>> | 100% | 46,137 psi | 72% | 3130 fps | 99.5% |
| Norma MRP | <<locked>> | 90% | 57,638 psi | 90% | 3297 fps | 100% |
| Norma URP | <<locked>> | 84% | 56,579 psi | 89% | 3186 fps | 100% |
| Ramshot Grand | <<locked>> | 92% | 56,318 psi | 88% | 3281 fps | 99.5% |
| Ramshot Hunter | <<locked>> | 84% | 55,593 psi | 87% | 3192 fps | 100% |
| Ramshot Magnum | <<locked>> | 94% | 55,042 psi | 86% | 3209 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,334 psi | 60% | 2090 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 82% | 54,781 psi | 86% | 3169 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 84% | 57,116 psi | 90% | 3261 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 54,926 psi | 86% | 3327 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 54,215 psi | 85% | 3278 fps | 98.5% |
| Rottweil R 904 | <<locked>> | 88% | 56,420 psi | 88% | 3179 fps | 99.2% |
| Rottweil R 905 | <<locked>> | 88% | 54,737 psi | 86% | 3189 fps | 99.7% |
| Rottweil R 907 | <<locked>> | 82% | 56,333 psi | 88% | 3150 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 82% | 55,071 psi | 86% | 3114 fps | 100% |
| Shooters World SW4350 | <<locked>> | 84% | 56,884 psi | 89% | 3166 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 84% | 57,725 psi | 90% | 3117 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 54,331 psi | 85% | 3186 fps | 99.7% |
| Somchem S361 | <<locked>> | 86% | 54,273 psi | 85% | 3107 fps | 98.5% |
| Somchem S365 | <<locked>> | 86% | 57,609 psi | 90% | 3186 fps | 100% |
| Somchem S385 | <<locked>> | 88% | 55,100 psi | 86% | 3156 fps | 99.9% |
| Vihtavuori N160 | <<locked>> | 82% | 54,505 psi | 85% | 3117 fps | 100% |
| Vihtavuori N165 | <<locked>> | 92% | 54,984 psi | 86% | 3140 fps | 99.8% |
| Vihtavuori N550 | <<locked>> | 84% | 57,406 psi | 90% | 3179 fps | 100% |
| Vihtavuori N555 | <<locked>> | 90% | 57,392 psi | 90% | 3212 fps | 100% |
| Vihtavuori N560 | <<locked>> | 90% | 57,217 psi | 90% | 3297 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 94% | 53,911 psi | 84% | 3212 fps | 98.8% |
| Vihtavuori N568 | <<locked>> | 98% | 54,882 psi | 86% | 3281 fps | 98.2% |
| Vihtavuori N570ᴾ | <<locked>> | 100% | 55,825 psi | 87% | 3340 fps | 96.6% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 57,740 psi | 90% | 3117 fps | 100% |
| Winchester 760 | <<locked>> | 82% | 56,246 psi | 88% | 3205 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 92% | 54,201 psi | 85% | 3271 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 54,969 psi | 86% | 3153 fps | 99.7% |
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% | 38,421 psi | 60% | 2815 fps | 98.8% |
| Accurate 4350 | <<locked>> | 80% | 50,952 psi | 80% | 3087 fps | 100% |
| Accurate MAGPRO | <<locked>> | 82% | 42,525 psi | 67% | 3005 fps | 95.3% |
| ADI AR 2209 | <<locked>> | 80% | 42,366 psi | 66% | 2956 fps | 97.7% |
| ADI AR 2213 | <<locked>> | 82% | 40,683 psi | 64% | 2949 fps | 95.9% |
| ADI AR 2217 | <<locked>> | 90% | 39,479 psi | 62% | 2913 fps | 95.9% |
| ADI AR 2225 | <<locked>> | 86% | 31,357 psi | 49% | 2740 fps | 95.7% |
| Alliant Reloder-16 | <<locked>> | 80% | 48,617 psi | 76% | 3091 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 42,409 psi | 66% | 2949 fps | 97.7% |
| Alliant Reloder-22 | <<locked>> | 80% | 38,290 psi | 60% | 2887 fps | 96.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 37,057 psi | 58% | 2844 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 32,024 psi | 50% | 2753 fps | 97.8% |
| Alliant Reloder-26 | <<locked>> | 80% | 41,234 psi | 65% | 3005 fps | 99.9% |
| Alliant Reloder-33 | <<locked>> | 98% | 48,892 psi | 77% | 3186 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 48,298 psi | 76% | 3045 fps | 95.2% |
| Bofors RP15 | <<locked>> | 80% | 35,650 psi | 56% | 2818 fps | 95.4% |
| Bofors RP30 | <<locked>> | 86% | 36,260 psi | 57% | 2861 fps | 95% |
| Bofors RP5 | <<locked>> | 80% | 38,290 psi | 60% | 2887 fps | 96.6% |
| Bofors RP7 | <<locked>> | 80% | 52,866 psi | 83% | 3091 fps | 99.8% |
| Hodgdon H1000 | <<locked>> | 86% | 37,536 psi | 59% | 2867 fps | 95.9% |
| Hodgdon H414 | <<locked>> | 80% | 52,489 psi | 82% | 3143 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 80% | 40,422 psi | 63% | 2887 fps | 95.1% |
| Hodgdon H4831 SC | <<locked>> | 82% | 42,627 psi | 67% | 2936 fps | 95.9% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 45,977 psi | 72% | 2963 fps | 100% |
| Hodgdon Retumbo | 58.2 gr | 82% | 33,388 psi | 52% | 2838 fps | 95.2% |
| Hodgdon Superformance | <<locked>> | 80% | 52,895 psi | 83% | 3179 fps | 99.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,934 psi | 44% | 1827 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 48,124 psi | 75% | 3015 fps | 99.4% |
| IMR 4451 Enduron | <<locked>> | 80% | 53,983 psi | 85% | 3110 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 48,153 psi | 75% | 3022 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 41,843 psi | 66% | 2887 fps | 95.9% |
| IMR 7828 SSC | <<locked>> | 82% | 39,233 psi | 61% | 2923 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 94% | 37,159 psi | 58% | 2904 fps | 95.2% |
| Lovex S065 | <<locked>> | 80% | 51,706 psi | 81% | 3058 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 50,111 psi | 79% | 3051 fps | 99.8% |
| Lovex S071 | <<locked>> | 80% | 33,011 psi | 52% | 2680 fps | 97.3% |
| Norma 204 | <<locked>> | 80% | 48,704 psi | 76% | 3064 fps | 98.8% |
| Norma 217 | <<locked>> | 90% | 32,474 psi | 51% | 2795 fps | 95.6% |
| Norma MRP | <<locked>> | 80% | 40,495 psi | 63% | 2966 fps | 98.5% |
| Norma URP | <<locked>> | 80% | 49,676 psi | 78% | 3071 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 38,899 psi | 61% | 2927 fps | 95.8% |
| Ramshot Hunter | <<locked>> | 80% | 48,675 psi | 76% | 3071 fps | 99.9% |
| Ramshot Magnum | <<locked>> | 80% | 32,372 psi | 51% | 2726 fps | 95.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,660 psi | 45% | 1870 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 51,053 psi | 80% | 3110 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 49,400 psi | 77% | 3133 fps | 100% |
| ReloadSwiss RS 76 | 62.3 gr | 82% | 32,605 psi | 51% | 2808 fps | 96.2% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 42,960 psi | 67% | 3054 fps | 95.8% |
| Rottweil R 904 | <<locked>> | 80% | 43,497 psi | 68% | 2933 fps | 96.9% |
| Rottweil R 905 | <<locked>> | 80% | 41,887 psi | 66% | 2936 fps | 97.7% |
| Rottweil R 907 | <<locked>> | 80% | 52,866 psi | 83% | 3091 fps | 99.8% |
| Shooters World Long Rifle | <<locked>> | 80% | 51,706 psi | 81% | 3058 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 50,111 psi | 79% | 3051 fps | 99.8% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 50,531 psi | 79% | 2999 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 41,539 psi | 65% | 2933 fps | 97.6% |
| Somchem S361 | <<locked>> | 80% | 44,411 psi | 70% | 2917 fps | 96.4% |
| Somchem S365 | <<locked>> | 80% | 47,021 psi | 74% | 3018 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 42,351 psi | 66% | 2913 fps | 98.5% |
| Vihtavuori N160 | <<locked>> | 80% | 51,082 psi | 80% | 3061 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 36,825 psi | 58% | 2776 fps | 96.7% |
| Vihtavuori N550 | <<locked>> | 80% | 50,343 psi | 79% | 3061 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 41,394 psi | 65% | 2927 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 40,437 psi | 63% | 2956 fps | 95.3% |
| Vihtavuori N565 | <<locked>> | 86% | 40,988 psi | 64% | 2949 fps | 95.8% |
| Vihtavuori N568 | <<locked>> | 92% | 44,251 psi | 69% | 3071 fps | 95.5% |
| Vihtavuori N570 | <<locked>> | 98% | 51,851 psi | 81% | 3264 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 50,357 psi | 79% | 3009 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 52,489 psi | 82% | 3143 fps | 99.9% |
| Winchester StaBALL HD | 58.4 gr | 80% | 33,953 psi | 53% | 2884 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 38,870 psi | 61% | 2831 fps | 96.7% |
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 70 powders for .257 Weath. Mag. loaded with the .257 | 115gr | Speer TBBC. Vihtavuori N570 delivers the highest muzzle velocity at 3,340 fps; across all powders the maximum-charge window runs from 2,041 fps to 3,340 fps. ADI AR 2217 gives the best case fill at 100 %, and 70 of the 70 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 59–90 %, leaving at least 10 % headroom. The 115.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-33 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. Hodgdon Retumbo, ReloadSwiss RS 76, Winchester StaBALL HD rank at the top here: for .257 Weath. Mag. with the .257 | 115gr | Speer TBBC 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.