Load Specifications
Load data in caliber .256 Mag. Gibbs with .257 | 95gr | Hammer HHT bullet and 51 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 IMR 4831.
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% | 42,772 psi | 87% | 2917 fps | 100% |
| Accurate 4064 | <<locked>> | 86% | 42,960 psi | 87% | 2956 fps | 100% |
| Accurate 4350 | <<locked>> | 94% | 41,916 psi | 85% | 2989 fps | 96.1% |
| ADI AR 2206H | <<locked>> | 82% | 44,353 psi | 90% | 2982 fps | 97.9% |
| ADI AR 2208 | <<locked>> | 86% | 42,772 psi | 87% | 2927 fps | 96.9% |
| Alliant Power Pro 2000-MR | <<locked>> | 84% | 43,366 psi | 88% | 3068 fps | 96.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 42,032 psi | 85% | 2946 fps | 98.3% |
| Alliant Reloder-15 | <<locked>> | 84% | 42,409 psi | 86% | 2959 fps | 97% |
| Alliant Reloder-16 | <<locked>> | 94% | 42,090 psi | 85% | 3012 fps | 96.3% |
| Alliant Reloder-17 | <<locked>> | 90% | 41,974 psi | 85% | 3038 fps | 98% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 43,729 psi | 89% | 2982 fps | 96.8% |
| Bofors RP3 | <<locked>> | 86% | 41,626 psi | 84% | 2946 fps | 98.3% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 43,758 psi | 89% | 3002 fps | 98.3% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 43,381 psi | 88% | 3015 fps | 98.6% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,925 psi | 71% | 1969 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 42,873 psi | 87% | 2936 fps | 98% |
| IMR 3031 | <<locked>> | 82% | 43,874 psi | 89% | 2995 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 41,916 psi | 85% | 2904 fps | 96.9% |
| IMR 4831 | <<locked>> | 96% | 43,279 psi | 88% | 3002 fps | 96.6% |
| IMR 4895 | <<locked>> | 84% | 43,468 psi | 88% | 2992 fps | 97.8% |
| Lovex D073.6 | <<locked>> | 82% | 43,163 psi | 88% | 2959 fps | 99.7% |
| Lovex S060 | <<locked>> | 82% | 44,527 psi | 90% | 2917 fps | 98% |
| Lovex S062 | <<locked>> | 86% | 44,570 psi | 90% | 2969 fps | 99% |
| Norma 201 | <<locked>> | 82% | 43,105 psi | 87% | 2927 fps | 98.7% |
| Norma 202 | <<locked>> | 82% | 43,468 psi | 88% | 2943 fps | 99.9% |
| Norma 203B | <<locked>> | 84% | 41,727 psi | 85% | 2946 fps | 97.4% |
| Norma URP | <<locked>> | 94% | 42,076 psi | 85% | 2992 fps | 96% |
| Ramshot Big Game | <<locked>> | 84% | 41,771 psi | 85% | 2963 fps | 97.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,215 psi | 71% | 2011 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 41,872 psi | 85% | 3012 fps | 96.8% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 41,843 psi | 85% | 3051 fps | 99.6% |
| Rottweil R 902 | <<locked>> | 84% | 43,729 psi | 89% | 2930 fps | 98.8% |
| Rottweil R 903 | <<locked>> | 90% | 44,585 psi | 90% | 3002 fps | 98.6% |
| Shooters World Match Rifle | <<locked>> | 82% | 43,163 psi | 88% | 2959 fps | 99.7% |
| Shooters World Precision | <<locked>> | 86% | 44,570 psi | 90% | 2969 fps | 99% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 43,366 psi | 88% | 3005 fps | 97.7% |
| SNPE Vectan SP 7 | <<locked>> | 82% | 44,498 psi | 90% | 2959 fps | 96.1% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 42,975 psi | 87% | 2946 fps | 97.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 42,003 psi | 85% | 2841 fps | 100% |
| Somchem S335 | <<locked>> | 82% | 44,266 psi | 90% | 2890 fps | 100% |
| Somchem S341 | <<locked>> | 82% | 44,556 psi | 90% | 2963 fps | 97.9% |
| Somchem S355 | <<locked>> | 88% | 42,583 psi | 86% | 2949 fps | 98% |
| Somchem S365 | <<locked>> | 98% | 43,033 psi | 87% | 3058 fps | 99.3% |
| Vihtavuori N135 | <<locked>> | 84% | 42,902 psi | 87% | 2917 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 44,048 psi | 89% | 2927 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 43,569 psi | 88% | 2936 fps | 99.2% |
| Vihtavuori N160 | <<locked>> | 94% | 44,295 psi | 90% | 2999 fps | 96.6% |
| Vihtavuori N540 | <<locked>> | 84% | 42,424 psi | 86% | 2910 fps | 99.8% |
| Vihtavuori N550 | <<locked>> | 94% | 43,598 psi | 88% | 2999 fps | 96.2% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 41,916 psi | 85% | 2917 fps | 98.1% |
| Winchester StaBALL Match | <<locked>> | 82% | 42,221 psi | 86% | 2943 fps | 98% |
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% | 37,188 psi | 75% | 2805 fps | 100% |
| Accurate 4064 | <<locked>> | 80% | 35,201 psi | 71% | 2782 fps | 99.1% |
| Accurate 4350 | <<locked>> | 92% | 39,175 psi | 79% | 2927 fps | 95.2% |
| ADI AR 2206H | <<locked>> | 80% | 41,408 psi | 84% | 2917 fps | 97.2% |
| ADI AR 2208 | <<locked>> | 82% | 37,536 psi | 76% | 2805 fps | 95.3% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 40,190 psi | 82% | 2992 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 34,534 psi | 70% | 2766 fps | 96.1% |
| Alliant Reloder-15 | <<locked>> | 80% | 37,188 psi | 75% | 2835 fps | 95.4% |
| Alliant Reloder-16 | <<locked>> | 92% | 39,320 psi | 80% | 2943 fps | 95.3% |
| Alliant Reloder-17 | 42.3 gr | 84% | 34,156 psi | 69% | 2835 fps | 95.1% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 40,596 psi | 82% | 2910 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 33,765 psi | 68% | 2756 fps | 95.9% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 33,692 psi | 68% | 2762 fps | 95.1% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 37,681 psi | 76% | 2884 fps | 97.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,715 psi | 52% | 1755 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 40,292 psi | 82% | 2881 fps | 97.4% |
| IMR 3031 | <<locked>> | 80% | 41,060 psi | 83% | 2940 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 36,970 psi | 75% | 2789 fps | 95.4% |
| IMR 4831 | 44.8 gr | 94% | 40,306 psi | 82% | 2936 fps | 95.7% |
| IMR 4895 | <<locked>> | 80% | 38,058 psi | 77% | 2871 fps | 96.4% |
| Lovex D073.6 | <<locked>> | 80% | 40,190 psi | 82% | 2894 fps | 99.3% |
| Lovex S060 | <<locked>> | 80% | 41,945 psi | 85% | 2864 fps | 97.4% |
| Lovex S062 | <<locked>> | 80% | 36,724 psi | 74% | 2795 fps | 97.3% |
| Norma 201 | <<locked>> | 80% | 40,509 psi | 82% | 2871 fps | 98.2% |
| Norma 202 | <<locked>> | 80% | 40,814 psi | 83% | 2887 fps | 99.7% |
| Norma 203B | <<locked>> | 80% | 36,535 psi | 74% | 2822 fps | 95.8% |
| Norma URP | <<locked>> | 92% | 39,508 psi | 80% | 2930 fps | 95.2% |
| Ramshot Big Game | <<locked>> | 80% | 36,114 psi | 73% | 2828 fps | 95.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,063 psi | 53% | 1801 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 38,899 psi | 79% | 2943 fps | 95.8% |
| ReloadSwiss RS 60 | 40.3 gr | 80% | 31,792 psi | 64% | 2779 fps | 96.8% |
| Rottweil R 902 | <<locked>> | 80% | 38,319 psi | 78% | 2812 fps | 97.7% |
| Rottweil R 903 | <<locked>> | 82% | 33,910 psi | 69% | 2756 fps | 95.6% |
| Shooters World Match Rifle | <<locked>> | 80% | 40,190 psi | 82% | 2894 fps | 99.3% |
| Shooters World Precision | <<locked>> | 80% | 36,724 psi | 74% | 2795 fps | 97.3% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 35,491 psi | 72% | 2818 fps | 95.2% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 41,539 psi | 84% | 2894 fps | 95.2% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 40,147 psi | 81% | 2884 fps | 96.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 34,664 psi | 70% | 2680 fps | 99.4% |
| Somchem S335 | <<locked>> | 80% | 41,640 psi | 84% | 2838 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 41,307 psi | 84% | 2897 fps | 97.2% |
| Somchem S355 | <<locked>> | 82% | 35,027 psi | 71% | 2772 fps | 95.8% |
| Somchem S365 | <<locked>> | 88% | 30,647 psi | 62% | 2736 fps | 95.4% |
| Vihtavuori N135 | <<locked>> | 80% | 37,637 psi | 76% | 2808 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 38,609 psi | 78% | 2815 fps | 99.6% |
| Vihtavuori N150 | <<locked>> | 80% | 31,169 psi | 63% | 2644 fps | 95.9% |
| Vihtavuori N160 | <<locked>> | 92% | 41,568 psi | 84% | 2940 fps | 95.8% |
| Vihtavuori N540 | <<locked>> | 80% | 36,999 psi | 75% | 2792 fps | 99.1% |
| Vihtavuori N550 | <<locked>> | 92% | 40,669 psi | 82% | 2933 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 34,156 psi | 69% | 2730 fps | 95.5% |
| Winchester StaBALL Match | <<locked>> | 80% | 39,392 psi | 80% | 2884 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 77 powders for .256 Mag. Gibbs loaded with the .257 | 95gr | Hammer HHT. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,068 fps; across all powders the maximum-charge window runs from 1,969 fps to 3,068 fps. Accurate 3100 gives the best case fill at 100 %, and 77 of the 77 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (340 MPa), the top charges use 65–90 %, leaving at least 10 % headroom. The 95.0 gr projectile in 0.257" calls for a 1:9.5 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. ReloadSwiss RS 60, Alliant Reloder-17, IMR 4831 rank at the top here: for .256 Mag. Gibbs with the .257 | 95gr | Hammer HHT they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 2700, Accurate 3100, Alliant Reloder-26 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.