Load Specifications
Load data in caliber .256 Mag. Gibbs with .257 | 86gr | Winchester SPRN bullet and 45 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 60, Alliant Reloder-17 and SNPE Vectan SP 11.
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: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 84% | 42,264 psi | 86% | 3038 fps | 100% |
| Accurate 4064 | <<locked>> | 86% | 42,554 psi | 86% | 3077 fps | 99.7% |
| ADI AR 2206H | <<locked>> | 82% | 43,729 psi | 89% | 3097 fps | 97% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 44,121 psi | 89% | 3120 fps | 98% |
| Alliant Reloder-15 | <<locked>> | 86% | 44,585 psi | 90% | 3133 fps | 96.7% |
| Alliant Reloder-17 | <<locked>> | 92% | 44,382 psi | 90% | 3219 fps | 97.7% |
| Bofors RP3 | <<locked>> | 88% | 44,063 psi | 89% | 3127 fps | 98.1% |
| Hodgdon BL-C2 | <<locked>> | 82% | 44,483 psi | 90% | 3130 fps | 98.8% |
| Hodgdon H4895 | <<locked>> | 82% | 44,121 psi | 89% | 3110 fps | 97.6% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 42,975 psi | 87% | 3107 fps | 97.3% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 42,627 psi | 86% | 3127 fps | 97.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,809 psi | 71% | 2073 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 42,235 psi | 86% | 3051 fps | 97.1% |
| IMR 3031 | <<locked>> | 82% | 43,221 psi | 88% | 3120 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 44,179 psi | 90% | 3077 fps | 96.6% |
| IMR 4895 | <<locked>> | 84% | 43,018 psi | 87% | 3110 fps | 96.9% |
| Lovex D073.6 | <<locked>> | 82% | 42,511 psi | 86% | 3074 fps | 99.2% |
| Lovex S060 | <<locked>> | 82% | 44,077 psi | 89% | 3035 fps | 97.1% |
| Lovex S062 | <<locked>> | 86% | 43,918 psi | 89% | 3084 fps | 98.3% |
| Norma 201 | <<locked>> | 82% | 42,772 psi | 87% | 3048 fps | 98% |
| Norma 202 | <<locked>> | 82% | 42,931 psi | 87% | 3064 fps | 99.6% |
| Norma 203B | <<locked>> | 86% | 43,830 psi | 89% | 3117 fps | 97.1% |
| Ramshot Big Game | <<locked>> | 86% | 43,743 psi | 89% | 3130 fps | 96.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,114 psi | 71% | 2119 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 84% | 43,874 psi | 89% | 3189 fps | 96.4% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 44,092 psi | 89% | 3228 fps | 99.5% |
| Rottweil R 902 | <<locked>> | 84% | 43,337 psi | 88% | 3051 fps | 98.1% |
| Rottweil R 903 | <<locked>> | 90% | 43,961 psi | 89% | 3114 fps | 97.8% |
| Shooters World Match Rifle | <<locked>> | 82% | 42,511 psi | 86% | 3074 fps | 99.2% |
| Shooters World Precision | <<locked>> | 86% | 43,918 psi | 89% | 3084 fps | 98.3% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 42,786 psi | 87% | 3117 fps | 96.7% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 42,235 psi | 86% | 3058 fps | 96.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 44,396 psi | 90% | 3015 fps | 99.7% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 44,353 psi | 90% | 3015 fps | 100% |
| Somchem S335 | <<locked>> | 82% | 43,888 psi | 89% | 3015 fps | 99.9% |
| Somchem S341 | <<locked>> | 82% | 43,816 psi | 89% | 3074 fps | 96.9% |
| Somchem S355 | <<locked>> | 88% | 42,148 psi | 85% | 3064 fps | 97.1% |
| Somchem S365 | <<locked>> | 98% | 42,105 psi | 85% | 3163 fps | 98.5% |
| Vihtavuori N133 | <<locked>> | 82% | 44,570 psi | 90% | 3015 fps | 100% |
| Vihtavuori N135 | <<locked>> | 84% | 42,409 psi | 86% | 3041 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 43,381 psi | 88% | 3045 fps | 99.8% |
| Vihtavuori N150 | <<locked>> | 90% | 42,931 psi | 87% | 3051 fps | 98.5% |
| Vihtavuori N540 | <<locked>> | 84% | 41,989 psi | 85% | 3028 fps | 99.4% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 44,454 psi | 90% | 3091 fps | 97.9% |
| Winchester StaBALL Match | <<locked>> | 84% | 44,498 psi | 90% | 3120 fps | 97.8% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 80% | 37,014 psi | 75% | 2923 fps | 100% |
| Accurate 4064 | <<locked>> | 80% | 34,998 psi | 71% | 2900 fps | 98.5% |
| ADI AR 2206H | <<locked>> | 80% | 40,959 psi | 83% | 3035 fps | 96.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 36,419 psi | 74% | 2936 fps | 95.8% |
| Alliant Reloder-15 | <<locked>> | 82% | 39,320 psi | 80% | 3009 fps | 95% |
| Alliant Reloder-17 | 45.8 gr | 88% | 38,696 psi | 78% | 3077 fps | 95.9% |
| Bofors RP3 | <<locked>> | 82% | 35,911 psi | 73% | 2933 fps | 95.7% |
| Hodgdon BL-C2 | <<locked>> | 80% | 41,640 psi | 84% | 3068 fps | 98.2% |
| Hodgdon H4895 | <<locked>> | 80% | 41,321 psi | 84% | 3048 fps | 96.9% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 37,840 psi | 77% | 2986 fps | 95.7% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 37,057 psi | 75% | 2992 fps | 96.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,947 psi | 53% | 1860 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 39,537 psi | 80% | 2989 fps | 96.3% |
| IMR 3031 | <<locked>> | 80% | 40,292 psi | 82% | 3058 fps | 99.9% |
| IMR 4064 | <<locked>> | 82% | 38,943 psi | 79% | 2956 fps | 95% |
| IMR 4895 | <<locked>> | 80% | 37,681 psi | 76% | 2982 fps | 95.2% |
| Lovex D073.6 | <<locked>> | 80% | 39,711 psi | 81% | 3012 fps | 98.7% |
| Lovex S060 | <<locked>> | 80% | 41,336 psi | 84% | 2972 fps | 96.4% |
| Lovex S062 | <<locked>> | 80% | 36,274 psi | 74% | 2904 fps | 96.2% |
| Norma 201 | <<locked>> | 80% | 40,074 psi | 81% | 2986 fps | 97.4% |
| Norma 202 | <<locked>> | 80% | 40,176 psi | 81% | 3002 fps | 99.2% |
| Norma 203B | <<locked>> | 82% | 38,682 psi | 78% | 2999 fps | 95.5% |
| Ramshot Big Game | <<locked>> | 82% | 38,130 psi | 77% | 2999 fps | 95% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,020 psi | 53% | 1900 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 40,930 psi | 83% | 3117 fps | 95.5% |
| ReloadSwiss RS 60 | 41.6 gr | 80% | 31,401 psi | 64% | 2874 fps | 95.2% |
| Rottweil R 902 | <<locked>> | 80% | 38,000 psi | 77% | 2927 fps | 96.7% |
| Rottweil R 903 | <<locked>> | 84% | 36,056 psi | 73% | 2927 fps | 95.4% |
| Shooters World Match Rifle | <<locked>> | 80% | 39,711 psi | 81% | 3012 fps | 98.7% |
| Shooters World Precision | <<locked>> | 80% | 36,274 psi | 74% | 2904 fps | 96.2% |
| SNPE Vectan SP 11 | 44 gr | 86% | 39,798 psi | 81% | 3048 fps | 95.7% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 39,566 psi | 80% | 2992 fps | 95.8% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 41,524 psi | 84% | 2956 fps | 99.4% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 34,287 psi | 70% | 2792 fps | 98.8% |
| Somchem S335 | <<locked>> | 80% | 41,147 psi | 83% | 2956 fps | 99.7% |
| Somchem S341 | <<locked>> | 80% | 40,799 psi | 83% | 3009 fps | 96.1% |
| Somchem S355 | <<locked>> | 84% | 36,898 psi | 75% | 2936 fps | 95.5% |
| Somchem S365 | <<locked>> | 90% | 32,489 psi | 66% | 2904 fps | 95% |
| Vihtavuori N133 | <<locked>> | 80% | 41,713 psi | 85% | 2959 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 37,115 psi | 75% | 2927 fps | 99.9% |
| Vihtavuori N140 | <<locked>> | 80% | 37,942 psi | 77% | 2927 fps | 99.1% |
| Vihtavuori N150 | <<locked>> | 82% | 32,996 psi | 67% | 2808 fps | 95.6% |
| Vihtavuori N540 | <<locked>> | 80% | 36,622 psi | 74% | 2904 fps | 98.4% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 36,318 psi | 74% | 2897 fps | 95.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 38,740 psi | 79% | 2989 fps | 96.2% |
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 71 powders for .256 Mag. Gibbs loaded with the .257 | 86gr | Winchester SPRN. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,228 fps; across all powders the maximum-charge window runs from 2,073 fps to 3,228 fps. Alliant Reloder-23 gives the best case fill at 100 %, and 71 of the 71 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (340 MPa), the top charges use 71–90 %, leaving at least 10 % headroom. The 86.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-23, Alliant Reloder-26, Hodgdon TrailBoss 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. ReloadSwiss RS 60, Alliant Reloder-17, SNPE Vectan SP 11 rank at the top here: for .256 Mag. Gibbs with the .257 | 86gr | Winchester SPRN they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Alliant Reloder-23, Alliant Reloder-26, Hodgdon H380 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.