Load Specifications
Load data in caliber .256 Mag. Gibbs with .257 | 80gr | Impala LWHV LS bullet and 37 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- TS 15.5 and Somchem S365.
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% | 43,526 psi | 88% | 3133 fps | 100% |
| Accurate 4064 | <<locked>> | 86% | 43,279 psi | 88% | 3159 fps | 99.4% |
| ADI AR 2206H | <<locked>> | 82% | 43,540 psi | 88% | 3156 fps | 95.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 43,874 psi | 89% | 3179 fps | 97% |
| Alliant Reloder-17 | <<locked>> | 92% | 43,627 psi | 88% | 3258 fps | 96.3% |
| Bofors RP3 | <<locked>> | 88% | 44,135 psi | 90% | 3192 fps | 97.2% |
| Hodgdon BL-C2 | <<locked>> | 82% | 44,280 psi | 90% | 3196 fps | 98% |
| Hodgdon H4895 | <<locked>> | 82% | 43,830 psi | 89% | 3173 fps | 96.6% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 42,525 psi | 86% | 3156 fps | 96% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 42,192 psi | 86% | 3182 fps | 96.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,157 psi | 71% | 2133 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 44,570 psi | 90% | 3169 fps | 96.7% |
| IMR 3031 | <<locked>> | 82% | 42,830 psi | 87% | 3189 fps | 99.9% |
| Lovex D073.6 | <<locked>> | 82% | 42,598 psi | 86% | 3143 fps | 98.5% |
| Lovex S060 | <<locked>> | 82% | 43,685 psi | 89% | 3087 fps | 96% |
| Lovex S062 | <<locked>> | 86% | 43,932 psi | 89% | 3150 fps | 97.5% |
| Norma 201 | <<locked>> | 82% | 43,294 psi | 88% | 3120 fps | 97.3% |
| Norma 202 | <<locked>> | 82% | 42,975 psi | 87% | 3133 fps | 99.1% |
| Norma 203B | <<locked>> | 86% | 43,656 psi | 89% | 3179 fps | 96% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,520 psi | 72% | 2182 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 43,584 psi | 88% | 3281 fps | 98.7% |
| Rottweil R 902 | <<locked>> | 84% | 43,555 psi | 88% | 3117 fps | 97.3% |
| Rottweil R 903 | <<locked>> | 90% | 44,005 psi | 89% | 3179 fps | 96.8% |
| Shooters World Match Rifle | <<locked>> | 82% | 42,598 psi | 86% | 3143 fps | 98.5% |
| Shooters World Precision | <<locked>> | 86% | 43,932 psi | 89% | 3150 fps | 97.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 44,382 psi | 90% | 3081 fps | 99.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 43,903 psi | 89% | 3074 fps | 99.7% |
| Somchem S335 | <<locked>> | 82% | 44,135 psi | 90% | 3084 fps | 99.6% |
| Somchem S355 | <<locked>> | 88% | 42,192 psi | 86% | 3127 fps | 96.1% |
| Somchem S365ᴾ | <<locked>> | 100% | 44,324 psi | 90% | 3274 fps | 98.1% |
| Vihtavuori N133 | <<locked>> | 82% | 44,309 psi | 90% | 3084 fps | 100% |
| Vihtavuori N135 | <<locked>> | 84% | 42,409 psi | 86% | 3114 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 43,004 psi | 87% | 3107 fps | 99.3% |
| Vihtavuori N150 | <<locked>> | 90% | 42,815 psi | 87% | 3110 fps | 97.7% |
| Vihtavuori N540 | <<locked>> | 86% | 44,353 psi | 90% | 3146 fps | 99.2% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 43,903 psi | 89% | 3133 fps | 96.6% |
| Winchester StaBALL Match | <<locked>> | 84% | 44,150 psi | 90% | 3179 fps | 96.8% |
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% | 38,435 psi | 78% | 3018 fps | 99.8% |
| Accurate 4064 | <<locked>> | 80% | 36,274 psi | 74% | 2989 fps | 98% |
| ADI AR 2206H | <<locked>> | 80% | 40,901 psi | 83% | 3091 fps | 95% |
| Alliant Reloder- TS 15.5 | 39.9 gr | 84% | 38,856 psi | 79% | 3058 fps | 95.5% |
| Alliant Reloder-17 | <<locked>> | 90% | 41,002 psi | 83% | 3189 fps | 95.4% |
| Bofors RP3 | <<locked>> | 84% | 38,754 psi | 79% | 3064 fps | 95.6% |
| Hodgdon BL-C2 | <<locked>> | 80% | 41,568 psi | 84% | 3130 fps | 97.4% |
| Hodgdon H4895 | <<locked>> | 80% | 41,147 psi | 83% | 3107 fps | 95.8% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 40,161 psi | 81% | 3097 fps | 95.2% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 39,653 psi | 80% | 3117 fps | 95.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,165 psi | 53% | 1909 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 39,421 psi | 80% | 3048 fps | 95.2% |
| IMR 3031 | <<locked>> | 80% | 40,030 psi | 81% | 3123 fps | 99.7% |
| Lovex D073.6 | <<locked>> | 80% | 39,885 psi | 81% | 3077 fps | 98% |
| Lovex S060 | <<locked>> | 80% | 41,321 psi | 84% | 3031 fps | 95.3% |
| Lovex S062 | <<locked>> | 80% | 36,840 psi | 75% | 2972 fps | 95.3% |
| Norma 201 | <<locked>> | 80% | 40,640 psi | 82% | 3058 fps | 96.5% |
| Norma 202 | <<locked>> | 80% | 40,321 psi | 82% | 3071 fps | 98.6% |
| Norma 203B | <<locked>> | 84% | 41,249 psi | 84% | 3123 fps | 95.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,585 psi | 54% | 1959 fps | 100% |
| ReloadSwiss RS 60 | 41.6 gr | 82% | 34,011 psi | 69% | 3005 fps | 95.1% |
| Rottweil R 902 | <<locked>> | 80% | 38,856 psi | 79% | 3002 fps | 96% |
| Rottweil R 903 | <<locked>> | 86% | 38,870 psi | 79% | 3058 fps | 95.3% |
| Shooters World Match Rifle | <<locked>> | 80% | 39,885 psi | 81% | 3077 fps | 98% |
| Shooters World Precision | <<locked>> | 80% | 36,840 psi | 75% | 2972 fps | 95.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 41,539 psi | 84% | 3018 fps | 98.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 34,447 psi | 70% | 2854 fps | 98.2% |
| Somchem S335 | <<locked>> | 80% | 41,481 psi | 84% | 3025 fps | 99.3% |
| Somchem S355 | <<locked>> | 86% | 39,581 psi | 80% | 3064 fps | 95.3% |
| Somchem S365 | 45.2 gr | 94% | 37,086 psi | 75% | 3091 fps | 95.8% |
| Vihtavuori N133 | <<locked>> | 80% | 41,539 psi | 84% | 3025 fps | 99.9% |
| Vihtavuori N135 | <<locked>> | 80% | 37,304 psi | 76% | 2999 fps | 99.7% |
| Vihtavuori N140 | <<locked>> | 80% | 38,072 psi | 77% | 2992 fps | 98.5% |
| Vihtavuori N150 | <<locked>> | 84% | 35,505 psi | 72% | 2933 fps | 95.5% |
| Vihtavuori N540 | <<locked>> | 80% | 36,985 psi | 75% | 2976 fps | 97.7% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 41,060 psi | 83% | 3068 fps | 95.7% |
| Winchester StaBALL Match | <<locked>> | 80% | 38,638 psi | 78% | 3048 fps | 95% |
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 63 powders for .256 Mag. Gibbs loaded with the .257 | 80gr | Impala LWHV LS. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,281 fps; across all powders the maximum-charge window runs from 2,133 fps to 3,281 fps. Alliant Reloder-23 gives the best case fill at 100 %, and 63 of the 63 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 80.0 gr projectile in 0.257" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. Alliant Reloder-23, Hodgdon TrailBoss, ReloadSwiss RS 14 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- TS 15.5, Somchem S365 rank at the top here: for .256 Mag. Gibbs with the .257 | 80gr | Impala LWHV LS they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 4350, Alliant Power Pro 2000-MR, Alliant Reloder-16 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.