Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 117gr | Hornady SST 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 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>> | 90% | 55,158 psi | 86% | 3114 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 55,753 psi | 87% | 3143 fps | 100% |
| Accurate High Country | <<locked>> | 88% | 56,840 psi | 89% | 3281 fps | 99.5% |
| Accurate MAGPRO | <<locked>> | 88% | 54,070 psi | 85% | 3219 fps | 98.4% |
| ADI AR 2209 | <<locked>> | 88% | 56,826 psi | 89% | 3212 fps | 99.8% |
| ADI AR 2213 | <<locked>> | 90% | 54,781 psi | 86% | 3219 fps | 99.2% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 57,029 psi | 89% | 3248 fps | 99.7% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 51,314 psi | 80% | 3205 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 56,913 psi | 89% | 3209 fps | 99.8% |
| Alliant Reloder-16 | <<locked>> | 84% | 56,898 psi | 89% | 3202 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 56,260 psi | 88% | 3199 fps | 99.8% |
| Alliant Reloder-22 | <<locked>> | 90% | 55,129 psi | 86% | 3215 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 92% | 56,724 psi | 89% | 3179 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 96% | 56,594 psi | 89% | 3248 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 88% | 57,551 psi | 90% | 3274 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 54,433 psi | 85% | 3268 fps | 97% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 55,825 psi | 87% | 3173 fps | 97.3% |
| Bofors RP15 | <<locked>> | 92% | 54,389 psi | 85% | 3199 fps | 99.7% |
| Bofors RP30 | <<locked>> | 98% | 56,420 psi | 88% | 3261 fps | 99.7% |
| Bofors RP5 | <<locked>> | 90% | 55,129 psi | 86% | 3215 fps | 99.8% |
| Bofors RP7 | <<locked>> | 82% | 57,116 psi | 90% | 3140 fps | 100% |
| Hodgdon H1000 | <<locked>> | 96% | 54,752 psi | 86% | 3212 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 82% | 57,130 psi | 90% | 3199 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 54,375 psi | 85% | 3150 fps | 98.7% |
| Hodgdon H4831 SC | <<locked>> | 90% | 56,971 psi | 89% | 3192 fps | 99.1% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 57,130 psi | 90% | 3120 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 55,637 psi | 87% | 3343 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,420 psi | 59% | 2031 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 55,637 psi | 87% | 3127 fps | 100% |
| IMR 4831 | <<locked>> | 84% | 56,260 psi | 88% | 3136 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 55,158 psi | 86% | 3133 fps | 98.9% |
| IMR 7828 SSC | <<locked>> | 92% | 56,797 psi | 89% | 3261 fps | 99.5% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 46,934 psi | 74% | 3107 fps | 98.4% |
| Lovex S065 | <<locked>> | 82% | 56,101 psi | 88% | 3107 fps | 100% |
| Lovex S070 | <<locked>> | 82% | 54,433 psi | 85% | 3107 fps | 100% |
| Lovex S071 | <<locked>> | 96% | 56,724 psi | 89% | 3140 fps | 100% |
| Norma 204 | <<locked>> | 84% | 56,884 psi | 89% | 3192 fps | 99.8% |
| Norma 217ᴾ | <<locked>> | 100% | 47,630 psi | 75% | 3136 fps | 99.8% |
| Norma MRP | <<locked>> | 88% | 55,129 psi | 86% | 3235 fps | 100% |
| Norma URP | <<locked>> | 84% | 57,740 psi | 90% | 3179 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 53,983 psi | 85% | 3222 fps | 99.4% |
| Ramshot Hunter | <<locked>> | 84% | 56,710 psi | 89% | 3189 fps | 100% |
| Ramshot Magnum | <<locked>> | 94% | 56,550 psi | 89% | 3212 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,392 psi | 60% | 2077 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 82% | 55,970 psi | 88% | 3166 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 54,331 psi | 85% | 3192 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 56,492 psi | 89% | 3330 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 55,724 psi | 87% | 3281 fps | 98.9% |
| Rottweil R 904 | <<locked>> | 88% | 57,464 psi | 90% | 3176 fps | 99.5% |
| Rottweil R 905 | <<locked>> | 88% | 55,883 psi | 88% | 3186 fps | 99.8% |
| Rottweil R 907 | <<locked>> | 82% | 57,116 psi | 90% | 3140 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 82% | 56,101 psi | 88% | 3107 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 54,433 psi | 85% | 3107 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 55,114 psi | 86% | 3058 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 55,477 psi | 87% | 3182 fps | 99.8% |
| Somchem S361 | <<locked>> | 86% | 55,448 psi | 87% | 3107 fps | 98.8% |
| Somchem S365 | <<locked>> | 84% | 55,100 psi | 86% | 3127 fps | 100% |
| Somchem S385 | <<locked>> | 88% | 56,405 psi | 88% | 3156 fps | 100% |
| Vihtavuori N160 | <<locked>> | 82% | 55,593 psi | 87% | 3110 fps | 100% |
| Vihtavuori N165 | <<locked>> | 92% | 56,318 psi | 88% | 3140 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 54,969 psi | 86% | 3120 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 55,245 psi | 87% | 3156 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 54,708 psi | 86% | 3232 fps | 98.9% |
| Vihtavuori N565 | <<locked>> | 94% | 55,332 psi | 87% | 3219 fps | 99.2% |
| Vihtavuori N568 | <<locked>> | 98% | 56,376 psi | 88% | 3284 fps | 98.6% |
| Vihtavuori N570ᴾ | <<locked>> | 100% | 57,406 psi | 90% | 3346 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 55,230 psi | 87% | 3061 fps | 100% |
| Winchester 760 | <<locked>> | 82% | 57,363 psi | 90% | 3205 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 92% | 56,101 psi | 88% | 3274 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 56,318 psi | 88% | 3153 fps | 99.8% |
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% | 39,363 psi | 62% | 2818 fps | 99.1% |
| Accurate 4350 | <<locked>> | 80% | 52,141 psi | 82% | 3084 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 43,004 psi | 67% | 3009 fps | 97.1% |
| Accurate MAGPRO | <<locked>> | 82% | 43,569 psi | 68% | 3009 fps | 95.9% |
| ADI AR 2209 | <<locked>> | 80% | 43,366 psi | 68% | 2956 fps | 98.1% |
| ADI AR 2213 | <<locked>> | 80% | 38,725 psi | 61% | 2881 fps | 95.5% |
| ADI AR 2217 | <<locked>> | 88% | 37,768 psi | 59% | 2851 fps | 95.5% |
| ADI AR 2225 | <<locked>> | 84% | 30,110 psi | 47% | 2680 fps | 95.3% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 43,729 psi | 69% | 2956 fps | 98.2% |
| Alliant Reloder-16 | <<locked>> | 80% | 49,777 psi | 78% | 3087 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 43,323 psi | 68% | 2949 fps | 98.1% |
| Alliant Reloder-22 | <<locked>> | 80% | 39,262 psi | 62% | 2890 fps | 97.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 38,087 psi | 60% | 2844 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 32,866 psi | 52% | 2756 fps | 98.3% |
| Alliant Reloder-26 | <<locked>> | 80% | 42,598 psi | 67% | 3012 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 50,299 psi | 79% | 3192 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 49,284 psi | 77% | 3048 fps | 95.8% |
| Bofors RP15 | <<locked>> | 80% | 36,593 psi | 57% | 2822 fps | 96% |
| Bofors RP30 | <<locked>> | 86% | 37,449 psi | 59% | 2871 fps | 95.7% |
| Bofors RP5 | <<locked>> | 80% | 39,262 psi | 62% | 2890 fps | 97.1% |
| Bofors RP7 | <<locked>> | 80% | 53,606 psi | 84% | 3081 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 84% | 35,897 psi | 56% | 2805 fps | 95.5% |
| Hodgdon H414 | <<locked>> | 80% | 53,577 psi | 84% | 3140 fps | 100% |
| Hodgdon H4831 | <<locked>> | 80% | 41,336 psi | 65% | 2890 fps | 95.7% |
| Hodgdon H4831 SC | <<locked>> | 80% | 40,567 psi | 64% | 2871 fps | 95.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 46,818 psi | 73% | 2953 fps | 100% |
| Hodgdon Retumbo | 58.7 gr | 82% | 34,243 psi | 54% | 2848 fps | 96% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,050 psi | 44% | 1818 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 49,081 psi | 77% | 3012 fps | 99.6% |
| IMR 4831 | <<locked>> | 80% | 49,226 psi | 77% | 3018 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 42,699 psi | 67% | 2887 fps | 96.4% |
| IMR 7828 SSC | <<locked>> | 80% | 37,347 psi | 59% | 2858 fps | 95% |
| IMR 8133 Enduron | <<locked>> | 94% | 38,145 psi | 60% | 2907 fps | 95.8% |
| Lovex S065 | <<locked>> | 80% | 52,692 psi | 83% | 3051 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 51,126 psi | 80% | 3048 fps | 99.9% |
| Lovex S071 | <<locked>> | 80% | 33,895 psi | 53% | 2684 fps | 97.8% |
| Norma 204 | <<locked>> | 80% | 49,763 psi | 78% | 3064 fps | 99.1% |
| Norma 217 | <<locked>> | 88% | 31,183 psi | 49% | 2736 fps | 95.2% |
| Norma MRP | <<locked>> | 80% | 41,539 psi | 65% | 2969 fps | 98.9% |
| Norma URP | <<locked>> | 80% | 50,720 psi | 79% | 3064 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 37,202 psi | 58% | 2864 fps | 95.4% |
| Ramshot Hunter | <<locked>> | 80% | 49,705 psi | 78% | 3068 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 33,388 psi | 52% | 2736 fps | 96% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,805 psi | 45% | 1860 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 52,214 psi | 82% | 3107 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 50,546 psi | 79% | 3130 fps | 100% |
| ReloadSwiss RS 76 | 61.3 gr | 80% | 31,140 psi | 49% | 2743 fps | 95.7% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 41,104 psi | 64% | 2989 fps | 95.4% |
| Rottweil R 904 | <<locked>> | 80% | 44,425 psi | 70% | 2933 fps | 97.4% |
| Rottweil R 905 | <<locked>> | 80% | 42,888 psi | 67% | 2940 fps | 98.1% |
| Rottweil R 907 | <<locked>> | 80% | 53,606 psi | 84% | 3081 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 52,692 psi | 83% | 3051 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 51,126 psi | 80% | 3048 fps | 99.9% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 51,445 psi | 81% | 2995 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 42,554 psi | 67% | 2933 fps | 98.1% |
| Somchem S361 | <<locked>> | 80% | 45,281 psi | 71% | 2917 fps | 96.9% |
| Somchem S365 | <<locked>> | 80% | 48,196 psi | 76% | 3015 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 43,308 psi | 68% | 2913 fps | 98.8% |
| Vihtavuori N160 | <<locked>> | 80% | 52,112 psi | 82% | 3058 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 37,710 psi | 59% | 2779 fps | 97.2% |
| Vihtavuori N550 | <<locked>> | 80% | 51,358 psi | 80% | 3058 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 42,453 psi | 67% | 2930 fps | 100% |
| Vihtavuori N560 | 59.5 gr | 80% | 41,423 psi | 65% | 2956 fps | 95.9% |
| Vihtavuori N565 | <<locked>> | 84% | 39,320 psi | 62% | 2890 fps | 95.5% |
| Vihtavuori N568 | <<locked>> | 90% | 42,395 psi | 66% | 3009 fps | 95.2% |
| Vihtavuori N570 | <<locked>> | 96% | 49,806 psi | 78% | 3205 fps | 95.4% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 51,372 psi | 81% | 3002 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 53,577 psi | 84% | 3140 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 35,186 psi | 55% | 2887 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 39,769 psi | 62% | 2835 fps | 97.3% |
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 | 117gr | Hornady SST. Vihtavuori N570 delivers the highest muzzle velocity at 3,346 fps; across all powders the maximum-charge window runs from 2,031 fps to 3,346 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 117.0 gr projectile in 0.257" calls for a 1:11.0 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, Vihtavuori N560 rank at the top here: for .257 Weath. Mag. with the .257 | 117gr | Hornady SST 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.