Load Specifications
Load data in caliber .256 Mag. Gibbs with .257 | 80gr | Barnes TTSX BT bullet and 47 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 Bofors RP3.
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 2015 | <<locked>> | 82% | 42,859 psi | 87% | 3110 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 42,931 psi | 87% | 3156 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 42,279 psi | 86% | 3156 fps | 98.6% |
| Accurate 4064 | <<locked>> | 90% | 42,975 psi | 87% | 3189 fps | 99.4% |
| ADI Benchmark 8208 | <<locked>> | 82% | 41,887 psi | 85% | 3123 fps | 96.9% |
| Alliant AR-Comp | <<locked>> | 84% | 43,613 psi | 88% | 3199 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 42,670 psi | 87% | 3182 fps | 96.9% |
| Alliant Reloder-17 | <<locked>> | 94% | 42,873 psi | 87% | 3264 fps | 96.3% |
| Bofors RP3 | <<locked>> | 90% | 42,279 psi | 86% | 3182 fps | 96.8% |
| Hodgdon Benchmark | <<locked>> | 82% | 44,063 psi | 89% | 3130 fps | 98% |
| Hodgdon BL-C2 | <<locked>> | 84% | 42,931 psi | 87% | 3192 fps | 97.8% |
| Hodgdon H4895 | <<locked>> | 84% | 42,815 psi | 87% | 3179 fps | 96.5% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 44,106 psi | 89% | 3255 fps | 97.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,229 psi | 69% | 2133 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 44,077 psi | 89% | 3189 fps | 96.7% |
| IMR 3031 | <<locked>> | 86% | 44,425 psi | 90% | 3251 fps | 100% |
| IMR 4895 | <<locked>> | 88% | 44,222 psi | 90% | 3235 fps | 96.3% |
| IMR 8208 XBR | <<locked>> | 82% | 41,887 psi | 85% | 3123 fps | 96.9% |
| Lovex D073.6 | <<locked>> | 86% | 43,685 psi | 89% | 3196 fps | 98.8% |
| Lovex S060 | <<locked>> | 84% | 42,960 psi | 87% | 3100 fps | 95.9% |
| Lovex S062 | <<locked>> | 88% | 42,206 psi | 86% | 3140 fps | 97.2% |
| Norma 201 | <<locked>> | 86% | 43,990 psi | 89% | 3169 fps | 97.5% |
| Norma 202 | <<locked>> | 86% | 44,512 psi | 90% | 3196 fps | 99.4% |
| Ramshot Wild Boar | <<locked>> | 84% | 44,135 psi | 90% | 3199 fps | 96.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,360 psi | 70% | 2178 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 42,859 psi | 87% | 3287 fps | 98.7% |
| Rottweil R 901 | <<locked>> | 82% | 42,337 psi | 86% | 3120 fps | 98.8% |
| Rottweil R 902 | <<locked>> | 88% | 44,541 psi | 90% | 3173 fps | 97.7% |
| Rottweil R 903 | <<locked>> | 92% | 42,177 psi | 86% | 3173 fps | 96.5% |
| Shooters World Match Rifle | <<locked>> | 86% | 43,685 psi | 89% | 3196 fps | 98.8% |
| Shooters World Precision | <<locked>> | 88% | 42,206 psi | 86% | 3140 fps | 97.2% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 43,990 psi | 89% | 3235 fps | 96.1% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 43,816 psi | 89% | 3182 fps | 96.1% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 43,178 psi | 88% | 3087 fps | 99.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 43,047 psi | 87% | 3084 fps | 99.7% |
| Somchem S335 | <<locked>> | 84% | 42,670 psi | 87% | 3084 fps | 99.6% |
| Somchem S355 | <<locked>> | 92% | 43,207 psi | 88% | 3179 fps | 96.5% |
| Somchem S365ᴾ | <<locked>> | 100% | 40,277 psi | 82% | 3205 fps | 97.2% |
| Vihtavuori N133 | <<locked>> | 84% | 43,265 psi | 88% | 3091 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 43,511 psi | 88% | 3166 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 42,076 psi | 85% | 3114 fps | 99.3% |
| Vihtavuori N150 | <<locked>> | 94% | 44,222 psi | 90% | 3169 fps | 98.1% |
| Vihtavuori N530 | <<locked>> | 82% | 41,800 psi | 85% | 3117 fps | 97% |
| Vihtavuori N540 | <<locked>> | 88% | 43,555 psi | 88% | 3159 fps | 99.2% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 43,236 psi | 88% | 3143 fps | 96.6% |
| Winchester 748 | <<locked>> | 84% | 43,976 psi | 89% | 3225 fps | 98.3% |
| Winchester StaBALL Match | <<locked>> | 86% | 43,120 psi | 87% | 3186 fps | 96.6% |
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 2015 | <<locked>> | 80% | 40,248 psi | 82% | 3054 fps | 99.9% |
| Accurate 2495 | <<locked>> | 80% | 32,474 psi | 66% | 2910 fps | 99.1% |
| Accurate 2520 | <<locked>> | 80% | 39,131 psi | 79% | 3087 fps | 97.9% |
| Accurate 4064 | <<locked>> | 80% | 30,734 psi | 62% | 2874 fps | 96.3% |
| ADI Benchmark 8208 | <<locked>> | 80% | 39,175 psi | 79% | 3058 fps | 96.1% |
| Alliant AR-Comp | <<locked>> | 80% | 37,811 psi | 77% | 3077 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 37,434 psi | 76% | 3054 fps | 95.2% |
| Alliant Reloder-17 | 47.2 gr | 92% | 40,059 psi | 81% | 3192 fps | 95.2% |
| Bofors RP3 | 42.5 gr | 86% | 36,637 psi | 74% | 3045 fps | 95% |
| Hodgdon Benchmark | <<locked>> | 80% | 41,249 psi | 84% | 3068 fps | 97.4% |
| Hodgdon BL-C2 | <<locked>> | 80% | 37,405 psi | 76% | 3061 fps | 96.3% |
| Hodgdon H4895 | <<locked>> | 82% | 40,016 psi | 81% | 3110 fps | 95.6% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 38,493 psi | 78% | 3120 fps | 95.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,266 psi | 51% | 1909 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 38,696 psi | 78% | 3058 fps | 95.1% |
| IMR 3031 | <<locked>> | 80% | 36,114 psi | 73% | 3061 fps | 99.1% |
| IMR 4895 | <<locked>> | 86% | 41,292 psi | 84% | 3166 fps | 95.4% |
| IMR 8208 XBR | <<locked>> | 80% | 39,175 psi | 79% | 3058 fps | 96.1% |
| Lovex D073.6 | <<locked>> | 80% | 35,317 psi | 72% | 2999 fps | 96.8% |
| Lovex S060 | <<locked>> | 82% | 40,451 psi | 82% | 3041 fps | 95.1% |
| Lovex S062 | <<locked>> | 84% | 37,057 psi | 75% | 3015 fps | 95.5% |
| Norma 201 | <<locked>> | 80% | 36,289 psi | 74% | 2982 fps | 95.2% |
| Norma 202 | <<locked>> | 80% | 36,390 psi | 74% | 3005 fps | 97.8% |
| Ramshot Wild Boar | <<locked>> | 82% | 41,002 psi | 83% | 3127 fps | 95.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,237 psi | 51% | 1952 fps | 100% |
| ReloadSwiss RS 60 | 44.1 gr | 86% | 34,751 psi | 70% | 3061 fps | 95.7% |
| Rottweil R 901 | <<locked>> | 80% | 39,508 psi | 80% | 3054 fps | 98.3% |
| Rottweil R 902 | <<locked>> | 82% | 36,550 psi | 74% | 2982 fps | 95.3% |
| Rottweil R 903 | <<locked>> | 90% | 39,276 psi | 80% | 3100 fps | 95.6% |
| Shooters World Match Rifle | <<locked>> | 80% | 35,317 psi | 72% | 2999 fps | 96.8% |
| Shooters World Precision | <<locked>> | 84% | 37,057 psi | 75% | 3015 fps | 95.5% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 41,118 psi | 83% | 3166 fps | 95.1% |
| SNPE Vectan SP 9 | <<locked>> | 84% | 41,017 psi | 83% | 3117 fps | 95.2% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 38,043 psi | 77% | 2969 fps | 98.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 31,082 psi | 63% | 2795 fps | 97.2% |
| Somchem S335 | <<locked>> | 80% | 37,550 psi | 76% | 2969 fps | 98.7% |
| Somchem S355 | <<locked>> | 90% | 40,321 psi | 82% | 3114 fps | 95.7% |
| Somchem S365 | <<locked>> | 96% | 35,331 psi | 72% | 3068 fps | 95.2% |
| Vihtavuori N133 | <<locked>> | 80% | 38,159 psi | 77% | 2979 fps | 99.7% |
| Vihtavuori N135 | <<locked>> | 80% | 33,243 psi | 67% | 2930 fps | 99.2% |
| Vihtavuori N140 | <<locked>> | 80% | 34,374 psi | 70% | 2930 fps | 97.6% |
| Vihtavuori N150 | <<locked>> | 86% | 33,808 psi | 69% | 2920 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 38,972 psi | 79% | 3048 fps | 96.2% |
| Vihtavuori N540 | <<locked>> | 80% | 33,170 psi | 67% | 2904 fps | 96.6% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 40,234 psi | 82% | 3074 fps | 95.6% |
| Winchester 748 | <<locked>> | 80% | 37,942 psi | 77% | 3084 fps | 96.8% |
| Winchester StaBALL Match | <<locked>> | 84% | 40,292 psi | 82% | 3117 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 73 powders for .256 Mag. Gibbs loaded with the .257 | 80gr | Barnes TTSX BT. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,301 fps; across all powders the maximum-charge window runs from 2,133 fps to 3,301 fps. Hodgdon Hybrid 100V gives the best case fill at 100 %, and 73 of the 73 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 80.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Hodgdon Hybrid 100V, Hodgdon TrailBoss, IMR 4831 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, Bofors RP3 rank at the top here: for .256 Mag. Gibbs with the .257 | 80gr | Barnes TTSX BT 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.