Load Specifications
Load data in caliber .256 Mag. Gibbs with .257 | 100gr | Rhino Solid Shank bullet and 44 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-17, Somchem S365 and ReloadSwiss RS 62.
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>> | 82% | 43,888 psi | 89% | 2861 fps | 100% |
| Accurate 4064 | <<locked>> | 84% | 44,324 psi | 90% | 2907 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 43,105 psi | 87% | 2949 fps | 97.1% |
| ADI AR 2208 | <<locked>> | 84% | 43,105 psi | 87% | 2871 fps | 97.6% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 43,584 psi | 88% | 3012 fps | 97.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 42,786 psi | 87% | 2894 fps | 98.8% |
| Alliant Reloder-15 | <<locked>> | 82% | 43,091 psi | 87% | 2904 fps | 97.7% |
| Alliant Reloder-16 | <<locked>> | 92% | 42,583 psi | 86% | 2959 fps | 97.2% |
| Alliant Reloder-17 | <<locked>> | 88% | 42,627 psi | 86% | 2989 fps | 98.7% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 39,218 psi | 80% | 2904 fps | 97.8% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 43,961 psi | 89% | 3071 fps | 96.9% |
| Bofors RP3 | <<locked>> | 84% | 42,670 psi | 87% | 2897 fps | 98.9% |
| Hodgdon H380 | <<locked>> | 84% | 43,410 psi | 88% | 2897 fps | 96.6% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 41,756 psi | 85% | 2897 fps | 98.4% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 44,106 psi | 89% | 2959 fps | 99.1% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,534 psi | 72% | 1929 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 42,380 psi | 86% | 2848 fps | 97.6% |
| IMR 4831 | <<locked>> | 94% | 44,251 psi | 90% | 2953 fps | 97.5% |
| IMR 4895 | <<locked>> | 82% | 44,179 psi | 90% | 2940 fps | 98.5% |
| Lovex S062 | <<locked>> | 82% | 42,380 psi | 86% | 2854 fps | 99.1% |
| Lovex S065 | <<locked>> | 90% | 44,556 psi | 90% | 2894 fps | 96% |
| Norma 203B | <<locked>> | 82% | 42,467 psi | 86% | 2894 fps | 98.1% |
| Norma URP | <<locked>> | 92% | 43,236 psi | 88% | 2949 fps | 97% |
| Ramshot Big Game | <<locked>> | 82% | 42,192 psi | 86% | 2907 fps | 97.9% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,940 psi | 73% | 1975 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 86% | 42,482 psi | 86% | 2999 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 43,062 psi | 87% | 2969 fps | 96.8% |
| Rottweil R 902 | <<locked>> | 82% | 44,411 psi | 90% | 2877 fps | 99.3% |
| Rottweil R 903 | <<locked>> | 86% | 42,830 psi | 87% | 2894 fps | 98.7% |
| Shooters World Long Rifle | <<locked>> | 90% | 44,556 psi | 90% | 2894 fps | 96% |
| Shooters World Precision | <<locked>> | 82% | 42,380 psi | 86% | 2854 fps | 99.1% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 44,077 psi | 89% | 2949 fps | 98.3% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 42,395 psi | 86% | 2779 fps | 100% |
| Somchem S355 | <<locked>> | 86% | 43,352 psi | 88% | 2897 fps | 98.7% |
| Somchem S365 | <<locked>> | 96% | 43,976 psi | 89% | 3012 fps | 99.7% |
| Vihtavuori N135 | <<locked>> | 82% | 43,685 psi | 89% | 2854 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 44,599 psi | 90% | 2867 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 44,222 psi | 90% | 2881 fps | 99.6% |
| Vihtavuori N160 | <<locked>> | 90% | 42,308 psi | 86% | 2890 fps | 96.7% |
| Vihtavuori N540 | <<locked>> | 82% | 43,076 psi | 87% | 2854 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 44,411 psi | 90% | 2946 fps | 97% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 42,873 psi | 87% | 2989 fps | 97.7% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 42,380 psi | 86% | 2867 fps | 98.7% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 35,027 psi | 71% | 2884 fps | 97.1% |
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% | 41,220 psi | 84% | 2808 fps | 100% |
| Accurate 4064 | <<locked>> | 80% | 38,972 psi | 79% | 2799 fps | 99.9% |
| Accurate 4350 | <<locked>> | 88% | 37,608 psi | 76% | 2825 fps | 95.4% |
| ADI AR 2208 | <<locked>> | 80% | 38,000 psi | 77% | 2753 fps | 96.2% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 40,756 psi | 83% | 2943 fps | 96.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 37,623 psi | 76% | 2776 fps | 97.7% |
| Alliant Reloder-15 | <<locked>> | 80% | 40,321 psi | 82% | 2841 fps | 97% |
| Alliant Reloder-16 | <<locked>> | 88% | 37,579 psi | 76% | 2838 fps | 95.5% |
| Alliant Reloder-17 | 40.7 gr | 80% | 32,460 psi | 66% | 2723 fps | 95.2% |
| Alliant Reloder-23 | <<locked>> | 94% | 32,416 psi | 66% | 2720 fps | 95% |
| Alliant Reloder-26 | <<locked>> | 98% | 40,770 psi | 83% | 2995 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 37,144 psi | 75% | 2776 fps | 97.7% |
| Hodgdon H380 | <<locked>> | 82% | 40,886 psi | 83% | 2844 fps | 95.9% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 32,416 psi | 66% | 2667 fps | 95.4% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 40,944 psi | 83% | 2894 fps | 98.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,382 psi | 54% | 1726 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 39,885 psi | 81% | 2792 fps | 97% |
| IMR 4831 | <<locked>> | 88% | 36,230 psi | 73% | 2772 fps | 95% |
| IMR 4895 | <<locked>> | 80% | 41,321 psi | 84% | 2877 fps | 97.9% |
| Lovex S062 | <<locked>> | 80% | 39,871 psi | 81% | 2799 fps | 98.6% |
| Lovex S065 | <<locked>> | 88% | 42,061 psi | 85% | 2841 fps | 95.2% |
| Norma 203B | <<locked>> | 80% | 39,711 psi | 81% | 2831 fps | 97.4% |
| Norma URP | <<locked>> | 88% | 37,681 psi | 76% | 2825 fps | 95.3% |
| Ramshot Big Game | <<locked>> | 80% | 39,465 psi | 80% | 2844 fps | 97.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,571 psi | 54% | 1762 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 34,548 psi | 70% | 2802 fps | 98.6% |
| ReloadSwiss RS 62 | 45.8 gr | 90% | 40,176 psi | 81% | 2907 fps | 95.9% |
| Rottweil R 902 | <<locked>> | 80% | 41,524 psi | 84% | 2815 fps | 98.9% |
| Rottweil R 903 | <<locked>> | 80% | 35,041 psi | 71% | 2717 fps | 96.7% |
| Shooters World Long Rifle | <<locked>> | 88% | 42,061 psi | 85% | 2841 fps | 95.2% |
| Shooters World Precision | <<locked>> | 80% | 39,871 psi | 81% | 2799 fps | 98.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 36,027 psi | 73% | 2766 fps | 96.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 37,478 psi | 76% | 2677 fps | 99.9% |
| Somchem S355 | <<locked>> | 80% | 35,940 psi | 73% | 2726 fps | 96.8% |
| Somchem S365 | 40.5 gr | 84% | 29,559 psi | 60% | 2644 fps | 95.6% |
| Vihtavuori N135 | <<locked>> | 80% | 41,017 psi | 83% | 2805 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 41,698 psi | 85% | 2812 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 34,098 psi | 69% | 2657 fps | 97.6% |
| Vihtavuori N160 | <<locked>> | 88% | 39,523 psi | 80% | 2831 fps | 95.8% |
| Vihtavuori N540 | <<locked>> | 80% | 40,306 psi | 82% | 2799 fps | 99.8% |
| Vihtavuori N550 | <<locked>> | 88% | 38,885 psi | 79% | 2828 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 94% | 34,954 psi | 71% | 2805 fps | 95.2% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 32,387 psi | 66% | 2625 fps | 95.5% |
| Winchester StaBALL HD | <<locked>> | 98% | 32,837 psi | 67% | 2808 fps | 95.8% |
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 44 powders for .256 Mag. Gibbs loaded with the .257 | 100gr | Rhino Solid Shank. Alliant Reloder-26 delivers the highest muzzle velocity at 3,071 fps; across all powders the maximum-charge window runs from 1,929 fps to 3,071 fps. Alliant Reloder-23 gives the best case fill at 100 %, and 44 of the 44 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 100.0 gr projectile in 0.257" calls for a 1:12.0 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. Alliant Reloder-17, Somchem S365, ReloadSwiss RS 62 rank at the top here: for .256 Mag. Gibbs with the .257 | 100gr | Rhino Solid Shank 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.