Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 120gr | Winchester Soft-Point bullet and 66 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 ReloadSwiss RS 80.
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% | 57,363 psi | 90% | 3117 fps | 100% |
| Accurate MAGPRO | <<locked>> | 90% | 57,130 psi | 90% | 3235 fps | 98.7% |
| ADI AR 2209 | <<locked>> | 86% | 54,824 psi | 86% | 3150 fps | 99.8% |
| ADI AR 2213 | <<locked>> | 90% | 56,985 psi | 89% | 3225 fps | 99.6% |
| ADI AR 2217 | <<locked>> | 98% | 55,347 psi | 87% | 3192 fps | 99.7% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 51,677 psi | 81% | 3222 fps | 96.6% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 53,751 psi | 84% | 3215 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 55,201 psi | 87% | 3146 fps | 99.8% |
| Alliant Reloder-16 | <<locked>> | 82% | 54,984 psi | 86% | 3140 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 54,592 psi | 86% | 3140 fps | 99.8% |
| Alliant Reloder-22 | <<locked>> | 90% | 57,363 psi | 90% | 3219 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 55,129 psi | 86% | 3117 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 55,245 psi | 87% | 3192 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 55,666 psi | 87% | 3209 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 57,000 psi | 89% | 3284 fps | 97.8% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 57,580 psi | 90% | 3176 fps | 98% |
| Bofors RP15 | <<locked>> | 92% | 56,536 psi | 89% | 3205 fps | 99.9% |
| Bofors RP30 | <<locked>> | 96% | 54,998 psi | 86% | 3205 fps | 99.7% |
| Bofors RP5 | <<locked>> | 90% | 57,363 psi | 90% | 3219 fps | 100% |
| Hodgdon H1000 | <<locked>> | 98% | 56,942 psi | 89% | 3219 fps | 100% |
| Hodgdon H4350 | <<locked>> | 82% | 56,231 psi | 88% | 3130 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 92% | 55,898 psi | 88% | 3146 fps | 99.1% |
| Hodgdon H4831 SC | <<locked>> | 88% | 55,129 psi | 86% | 3133 fps | 99% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 55,129 psi | 86% | 3054 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 54,070 psi | 85% | 3278 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,623 psi | 59% | 2014 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 57,363 psi | 90% | 3123 fps | 100% |
| IMR 4831 | <<locked>> | 86% | 55,854 psi | 88% | 3097 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 56,782 psi | 89% | 3133 fps | 99.3% |
| IMR 7828 SSC | <<locked>> | 88% | 55,042 psi | 86% | 3199 fps | 99.5% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 49,095 psi | 77% | 3117 fps | 99% |
| Lovex S065 | <<locked>> | 82% | 57,566 psi | 90% | 3100 fps | 100% |
| Lovex S070 | <<locked>> | 82% | 55,912 psi | 88% | 3097 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 55,288 psi | 87% | 3084 fps | 100% |
| Norma 204 | <<locked>> | 82% | 54,882 psi | 86% | 3127 fps | 99.8% |
| Norma 217ᴾ | <<locked>> | 100% | 49,980 psi | 78% | 3146 fps | 100% |
| Norma MRP | <<locked>> | 88% | 57,464 psi | 90% | 3238 fps | 100% |
| Norma URP | <<locked>> | 82% | 55,767 psi | 87% | 3114 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 55,056 psi | 86% | 3205 fps | 99.7% |
| Ramshot Hunter | <<locked>> | 82% | 54,824 psi | 86% | 3123 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 56,637 psi | 89% | 3179 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,406 psi | 60% | 2057 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 56,362 psi | 88% | 3189 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 54,781 psi | 86% | 3268 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 54,317 psi | 85% | 3225 fps | 98.9% |
| Rottweil R 904 | <<locked>> | 86% | 55,651 psi | 87% | 3117 fps | 99.5% |
| Rottweil R 905 | <<locked>> | 86% | 54,201 psi | 85% | 3127 fps | 99.8% |
| Shooters World Long Rifle | <<locked>> | 82% | 57,566 psi | 90% | 3100 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 55,912 psi | 88% | 3097 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 56,507 psi | 89% | 3051 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 57,392 psi | 90% | 3182 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 57,043 psi | 89% | 3107 fps | 99.3% |
| Somchem S365 | <<locked>> | 84% | 57,159 psi | 90% | 3120 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 54,491 psi | 85% | 3094 fps | 100% |
| Vihtavuori N160 | <<locked>> | 82% | 57,493 psi | 90% | 3107 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 54,549 psi | 85% | 3081 fps | 100% |
| Vihtavuori N170 | <<locked>> | 96% | 57,145 psi | 90% | 3153 fps | 96.2% |
| Vihtavuori N550 | <<locked>> | 82% | 56,768 psi | 89% | 3114 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 57,290 psi | 90% | 3153 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 56,913 psi | 89% | 3238 fps | 99.4% |
| Vihtavuori N565 | <<locked>> | 94% | 57,537 psi | 90% | 3222 fps | 99.6% |
| Vihtavuori N568 | <<locked>> | 96% | 54,969 psi | 86% | 3228 fps | 98.6% |
| Vihtavuori N570 | <<locked>> | 98% | 55,927 psi | 88% | 3287 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 56,971 psi | 89% | 3051 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 54,607 psi | 86% | 3212 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 55,492 psi | 87% | 3110 fps | 99.9% |
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% | 40,828 psi | 64% | 2822 fps | 99.5% |
| Accurate MAGPRO | <<locked>> | 82% | 42,917 psi | 67% | 2956 fps | 95.4% |
| ADI AR 2209 | <<locked>> | 80% | 44,802 psi | 70% | 2959 fps | 98.7% |
| ADI AR 2213 | <<locked>> | 80% | 40,248 psi | 63% | 2890 fps | 96.5% |
| ADI AR 2217 | <<locked>> | 86% | 36,680 psi | 57% | 2799 fps | 95.6% |
| ADI AR 2218 | <<locked>> | 98% | 48,124 psi | 75% | 3143 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 82% | 29,269 psi | 46% | 2628 fps | 95.2% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 45,165 psi | 71% | 2959 fps | 98.7% |
| Alliant Reloder-16 | <<locked>> | 80% | 51,488 psi | 81% | 3084 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 44,744 psi | 70% | 2953 fps | 98.7% |
| Alliant Reloder-22 | <<locked>> | 80% | 40,901 psi | 64% | 2900 fps | 97.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 39,595 psi | 62% | 2844 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 34,127 psi | 53% | 2762 fps | 98.9% |
| Alliant Reloder-26 | <<locked>> | 80% | 44,570 psi | 70% | 3015 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 49,023 psi | 77% | 3136 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 47,543 psi | 75% | 2986 fps | 95.7% |
| Bofors RP15 | <<locked>> | 80% | 37,985 psi | 60% | 2828 fps | 96.9% |
| Bofors RP30 | <<locked>> | 84% | 36,390 psi | 57% | 2815 fps | 95.7% |
| Bofors RP5 | <<locked>> | 80% | 40,901 psi | 64% | 2900 fps | 97.9% |
| Hodgdon H1000 | <<locked>> | 84% | 35,244 psi | 55% | 2762 fps | 95.6% |
| Hodgdon H4350 | <<locked>> | 80% | 52,823 psi | 83% | 3074 fps | 99.8% |
| Hodgdon H4831 | <<locked>> | 82% | 40,379 psi | 63% | 2838 fps | 95.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 42,105 psi | 66% | 2877 fps | 96.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 48,399 psi | 76% | 2946 fps | 100% |
| Hodgdon Retumbo | 58.1 gr | 80% | 33,272 psi | 52% | 2792 fps | 95.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,181 psi | 44% | 1804 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 50,502 psi | 79% | 3009 fps | 99.8% |
| IMR 4831 | <<locked>> | 80% | 46,340 psi | 73% | 2933 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 43,976 psi | 69% | 2887 fps | 97.1% |
| IMR 7828 SSC | <<locked>> | 80% | 41,408 psi | 65% | 2927 fps | 96.9% |
| IMR 8133 Enduron | <<locked>> | 92% | 37,391 psi | 59% | 2861 fps | 95.9% |
| Lovex S065 | <<locked>> | 80% | 54,157 psi | 85% | 3045 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 52,562 psi | 82% | 3041 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 35,244 psi | 55% | 2690 fps | 98.5% |
| Norma 204 | <<locked>> | 80% | 51,213 psi | 80% | 3061 fps | 99.5% |
| Norma 217 | <<locked>> | 86% | 30,560 psi | 48% | 2690 fps | 95.3% |
| Norma MRP | <<locked>> | 80% | 43,120 psi | 68% | 2972 fps | 99.3% |
| Norma URP | <<locked>> | 80% | 52,344 psi | 82% | 3058 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 43,526 psi | 68% | 2989 fps | 97.9% |
| Ramshot Hunter | <<locked>> | 80% | 51,256 psi | 80% | 3064 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 38,305 psi | 60% | 2835 fps | 98.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,950 psi | 45% | 1847 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 52,547 psi | 82% | 3130 fps | 100% |
| ReloadSwiss RS 76 | 62.2 gr | 80% | 32,489 psi | 51% | 2762 fps | 96.9% |
| ReloadSwiss RS 80 | 69 gr | 88% | 39,900 psi | 63% | 2930 fps | 95.3% |
| Rottweil R 904 | <<locked>> | 80% | 45,788 psi | 72% | 2933 fps | 98% |
| Rottweil R 905 | <<locked>> | 80% | 44,367 psi | 70% | 2943 fps | 98.7% |
| Shooters World Long Rifle | <<locked>> | 80% | 54,157 psi | 85% | 3045 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 52,562 psi | 82% | 3041 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 53,069 psi | 83% | 2992 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 44,019 psi | 69% | 2936 fps | 98.6% |
| Somchem S361 | <<locked>> | 80% | 46,717 psi | 73% | 2920 fps | 97.6% |
| Somchem S365 | <<locked>> | 80% | 49,922 psi | 78% | 3009 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 44,933 psi | 70% | 2920 fps | 99.3% |
| Vihtavuori N160 | <<locked>> | 80% | 53,693 psi | 84% | 3048 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 39,015 psi | 61% | 2782 fps | 97.9% |
| Vihtavuori N170 | <<locked>> | 94% | 53,417 psi | 84% | 3087 fps | 95.3% |
| Vihtavuori N550 | <<locked>> | 80% | 53,142 psi | 83% | 3058 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 44,048 psi | 69% | 2927 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 42,917 psi | 67% | 2963 fps | 96.8% |
| Vihtavuori N565 | <<locked>> | 82% | 38,203 psi | 60% | 2831 fps | 95.5% |
| Vihtavuori N568 | <<locked>> | 88% | 41,118 psi | 64% | 2946 fps | 95.1% |
| Vihtavuori N570 | <<locked>> | 94% | 48,428 psi | 76% | 3146 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 53,084 psi | 83% | 2995 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 37,028 psi | 58% | 2894 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 44,962 psi | 70% | 2917 fps | 98.7% |
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 66 powders for .257 Weath. Mag. loaded with the .257 | 120gr | Winchester Soft-Point. Vihtavuori N570 delivers the highest muzzle velocity at 3,287 fps; across all powders the maximum-charge window runs from 2,014 fps to 3,287 fps. ADI AR 2218 gives the best case fill at 100 %, and 66 of the 66 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 120.0 gr projectile in 0.257" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. ADI AR 2218, 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, ReloadSwiss RS 80 rank at the top here: for .257 Weath. Mag. with the .257 | 120gr | Winchester Soft-Point 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.