Load Specifications
Load data in caliber .256 Mag. Gibbs with .257 | 104gr | Peregrine VLR-5 bullet and 49 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Somchem S365, Alliant Reloder-17 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% | 42,366 psi | 86% | 2785 fps | 100% |
| Accurate 4064 | <<locked>> | 84% | 42,699 psi | 87% | 2828 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 41,698 psi | 85% | 2871 fps | 97% |
| ADI AR 2208 | <<locked>> | 84% | 42,119 psi | 85% | 2799 fps | 97.6% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 42,424 psi | 86% | 2933 fps | 97.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 44,338 psi | 90% | 2874 fps | 99.3% |
| Alliant Reloder-15 | <<locked>> | 82% | 41,916 psi | 85% | 2831 fps | 97.7% |
| Alliant Reloder-16 | <<locked>> | 94% | 44,193 psi | 90% | 2949 fps | 97.9% |
| Alliant Reloder-17 | <<locked>> | 90% | 44,599 psi | 90% | 2982 fps | 99.2% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 38,000 psi | 77% | 2828 fps | 97.7% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 42,656 psi | 87% | 2995 fps | 96.9% |
| Bofors RP3 | <<locked>> | 86% | 44,425 psi | 90% | 2887 fps | 99.3% |
| Hodgdon H380 | <<locked>> | 84% | 42,293 psi | 86% | 2828 fps | 96.6% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 43,714 psi | 89% | 2884 fps | 99% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 43,149 psi | 88% | 2890 fps | 99.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,143 psi | 71% | 1880 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 44,570 psi | 90% | 2858 fps | 99% |
| IMR 3031 | <<locked>> | 82% | 42,612 psi | 86% | 2841 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 43,918 psi | 89% | 2831 fps | 98.2% |
| IMR 4831 | <<locked>> | 98% | 43,685 psi | 89% | 2894 fps | 97.6% |
| IMR 4895 | <<locked>> | 82% | 42,975 psi | 87% | 2864 fps | 98.5% |
| Lovex S062 | <<locked>> | 84% | 44,019 psi | 89% | 2838 fps | 99.4% |
| Lovex S065 | <<locked>> | 90% | 43,555 psi | 88% | 2828 fps | 96% |
| Norma 203B | <<locked>> | 84% | 44,280 psi | 90% | 2881 fps | 98.7% |
| Norma URP | <<locked>> | 92% | 42,061 psi | 85% | 2877 fps | 97% |
| Ramshot Big Game | <<locked>> | 84% | 44,251 psi | 90% | 2900 fps | 98.5% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,520 psi | 72% | 1923 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 44,512 psi | 90% | 2946 fps | 98.2% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 44,353 psi | 90% | 2989 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 41,655 psi | 84% | 2894 fps | 96.7% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 42,018 psi | 85% | 2910 fps | 96% |
| Rottweil R 902 | <<locked>> | 82% | 43,004 psi | 87% | 2799 fps | 99.3% |
| Rottweil R 903 | <<locked>> | 88% | 44,338 psi | 90% | 2877 fps | 99.2% |
| Shooters World Long Rifle | <<locked>> | 90% | 43,555 psi | 88% | 2828 fps | 96% |
| Shooters World Precision | <<locked>> | 84% | 44,019 psi | 89% | 2838 fps | 99.4% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 42,902 psi | 87% | 2877 fps | 98.3% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 44,309 psi | 90% | 2762 fps | 100% |
| Somchem S355 | <<locked>> | 86% | 42,163 psi | 86% | 2825 fps | 98.6% |
| Somchem S365 | <<locked>> | 96% | 42,859 psi | 87% | 2936 fps | 99.7% |
| Unknown powder | <<locked>> | 90% | 42,859 psi | 87% | 2881 fps | 96.5% |
| Vihtavuori N135 | <<locked>> | 82% | 42,612 psi | 86% | 2785 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 43,439 psi | 88% | 2795 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 43,207 psi | 88% | 2812 fps | 99.6% |
| Vihtavuori N160 | <<locked>> | 92% | 43,874 psi | 89% | 2874 fps | 97.4% |
| Vihtavuori N540 | <<locked>> | 82% | 41,959 psi | 85% | 2782 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 43,308 psi | 88% | 2877 fps | 97% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 41,437 psi | 84% | 2910 fps | 97.7% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 44,135 psi | 90% | 2854 fps | 99.2% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 33,982 psi | 69% | 2808 fps | 97% |
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% | 39,610 psi | 80% | 2733 fps | 100% |
| Accurate 4064 | <<locked>> | 80% | 37,492 psi | 76% | 2720 fps | 99.8% |
| Accurate 4350 | <<locked>> | 88% | 36,361 psi | 74% | 2753 fps | 95.3% |
| ADI AR 2208 | <<locked>> | 80% | 37,144 psi | 75% | 2687 fps | 96.2% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 39,537 psi | 80% | 2864 fps | 96.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 36,637 psi | 74% | 2710 fps | 97.7% |
| Alliant Reloder-15 | <<locked>> | 80% | 39,378 psi | 80% | 2776 fps | 97.1% |
| Alliant Reloder-16 | <<locked>> | 88% | 36,680 psi | 74% | 2769 fps | 95.5% |
| Alliant Reloder-17 | 39.6 gr | 80% | 31,444 psi | 64% | 2654 fps | 95.1% |
| Alliant Reloder-23 | <<locked>> | 96% | 33,301 psi | 68% | 2703 fps | 95.9% |
| Alliant Reloder-26 | <<locked>> | 98% | 39,407 psi | 80% | 2917 fps | 95.7% |
| Bofors RP3 | <<locked>> | 80% | 35,998 psi | 73% | 2703 fps | 97.6% |
| Hodgdon H380 | <<locked>> | 82% | 39,668 psi | 80% | 2769 fps | 95.8% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 31,372 psi | 64% | 2595 fps | 95.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 37,637 psi | 76% | 2769 fps | 98.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,020 psi | 53% | 1677 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 39,015 psi | 79% | 2736 fps | 97.9% |
| IMR 3031 | <<locked>> | 80% | 39,856 psi | 81% | 2789 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 36,274 psi | 74% | 2661 fps | 96.2% |
| IMR 4831 | <<locked>> | 92% | 35,955 psi | 73% | 2723 fps | 95.3% |
| IMR 4895 | <<locked>> | 80% | 40,350 psi | 82% | 2808 fps | 97.9% |
| Lovex S062 | <<locked>> | 80% | 38,508 psi | 78% | 2723 fps | 98.5% |
| Lovex S065 | <<locked>> | 88% | 40,944 psi | 83% | 2772 fps | 95.2% |
| Norma 203B | <<locked>> | 80% | 38,725 psi | 79% | 2762 fps | 97.5% |
| Norma URP | <<locked>> | 88% | 36,651 psi | 74% | 2753 fps | 95.3% |
| Ramshot Big Game | <<locked>> | 80% | 38,189 psi | 77% | 2769 fps | 97.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,440 psi | 54% | 1722 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 41,336 psi | 84% | 2881 fps | 97.5% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 33,518 psi | 68% | 2730 fps | 98.5% |
| ReloadSwiss RS 62 | 44.5 gr | 90% | 38,783 psi | 79% | 2828 fps | 95.8% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 39,204 psi | 80% | 2844 fps | 95% |
| Rottweil R 902 | <<locked>> | 80% | 40,379 psi | 82% | 2743 fps | 98.9% |
| Rottweil R 903 | <<locked>> | 80% | 33,866 psi | 69% | 2644 fps | 96.7% |
| Shooters World Long Rifle | <<locked>> | 88% | 40,944 psi | 83% | 2772 fps | 95.2% |
| Shooters World Precision | <<locked>> | 80% | 38,508 psi | 78% | 2723 fps | 98.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 34,954 psi | 71% | 2697 fps | 96.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 36,492 psi | 74% | 2612 fps | 99.9% |
| Somchem S355 | <<locked>> | 80% | 34,853 psi | 71% | 2657 fps | 96.8% |
| Somchem S365 | 39.4 gr | 84% | 28,471 psi | 58% | 2569 fps | 95.4% |
| Unknown powder | <<locked>> | 88% | 40,205 psi | 82% | 2822 fps | 95.7% |
| Vihtavuori N135 | <<locked>> | 80% | 39,871 psi | 81% | 2733 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 40,785 psi | 83% | 2743 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 33,112 psi | 67% | 2589 fps | 97.6% |
| Vihtavuori N160 | <<locked>> | 88% | 38,580 psi | 78% | 2762 fps | 95.9% |
| Vihtavuori N540 | <<locked>> | 80% | 39,189 psi | 79% | 2726 fps | 99.8% |
| Vihtavuori N550 | <<locked>> | 88% | 37,898 psi | 77% | 2759 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 94% | 33,678 psi | 68% | 2730 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 31,531 psi | 64% | 2559 fps | 95.5% |
| Winchester StaBALL HD | <<locked>> | 98% | 31,720 psi | 64% | 2733 fps | 95.6% |
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 72 powders for .256 Mag. Gibbs loaded with the .257 | 104gr | Peregrine VLR-5. Alliant Reloder-26 delivers the highest muzzle velocity at 2,995 fps; across all powders the maximum-charge window runs from 1,880 fps to 2,995 fps. Accurate 3100 gives the best case fill at 100 %, and 72 of the 72 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (340 MPa), the top charges use 69–90 %, leaving at least 10 % headroom. The 104.0 gr projectile in 0.257" calls for a 1:8.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-23, Alliant Reloder-26 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. Somchem S365, Alliant Reloder-17, ReloadSwiss RS 62 rank at the top here: for .256 Mag. Gibbs with the .257 | 104gr | Peregrine VLR-5 they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 2700, Accurate 3100, Alliant Reloder-19 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.