Load Specifications
Load data in caliber .257 Roberts with .257 | 75gr | Barnes X 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- TS 15.5 and Rottweil R 903.
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% | 46,180 psi | 90% | 3222 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 44,701 psi | 87% | 3235 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 45,223 psi | 88% | 3264 fps | 98.7% |
| Accurate 4064 | <<locked>> | 88% | 44,686 psi | 87% | 3268 fps | 99.3% |
| ADI Benchmark 8208 | <<locked>> | 82% | 44,222 psi | 86% | 3219 fps | 96.9% |
| Alliant AR-Comp | <<locked>> | 84% | 46,035 psi | 89% | 3301 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 45,092 psi | 88% | 3281 fps | 96.9% |
| Alliant Reloder-17 | <<locked>> | 94% | 45,237 psi | 88% | 3363 fps | 96.3% |
| Bofors RP3 | <<locked>> | 90% | 45,353 psi | 88% | 3291 fps | 97% |
| Hodgdon Benchmark | <<locked>> | 82% | 46,224 psi | 90% | 3222 fps | 98% |
| Hodgdon BL-C2 | <<locked>> | 84% | 45,774 psi | 89% | 3301 fps | 97.9% |
| Hodgdon H4895 | <<locked>> | 84% | 45,368 psi | 88% | 3278 fps | 96.5% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 46,572 psi | 90% | 3356 fps | 97.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,940 psi | 68% | 2185 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 46,180 psi | 90% | 3281 fps | 96.7% |
| IMR 3031 | <<locked>> | 84% | 44,077 psi | 86% | 3297 fps | 99.9% |
| IMR 8208 XBR | <<locked>> | 82% | 44,222 psi | 86% | 3219 fps | 96.9% |
| Lovex D073.6 | <<locked>> | 84% | 43,961 psi | 85% | 3248 fps | 98.5% |
| Lovex S060 | <<locked>> | 84% | 45,353 psi | 88% | 3196 fps | 95.9% |
| Lovex S062 | <<locked>> | 88% | 45,165 psi | 88% | 3248 fps | 97.3% |
| Norma 201 | <<locked>> | 84% | 44,527 psi | 86% | 3222 fps | 97.1% |
| Norma 202 | <<locked>> | 84% | 44,266 psi | 86% | 3238 fps | 99% |
| Norma 203B | <<locked>> | 88% | 45,150 psi | 88% | 3287 fps | 95.9% |
| Ramshot Wild Boar | <<locked>> | 84% | 46,325 psi | 90% | 3291 fps | 96.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,273 psi | 69% | 2234 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 45,179 psi | 88% | 3386 fps | 98.6% |
| Rottweil R 901 | <<locked>> | 82% | 45,977 psi | 89% | 3238 fps | 99% |
| Rottweil R 902 | <<locked>> | 86% | 44,831 psi | 87% | 3219 fps | 97.1% |
| Rottweil R 903 | <<locked>> | 92% | 45,194 psi | 88% | 3281 fps | 96.7% |
| Shooters World Match Rifle | <<locked>> | 84% | 43,961 psi | 85% | 3248 fps | 98.5% |
| Shooters World Precision | <<locked>> | 88% | 45,165 psi | 88% | 3248 fps | 97.3% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 46,209 psi | 90% | 3330 fps | 96% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 46,224 psi | 90% | 3281 fps | 96.1% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 45,847 psi | 89% | 3186 fps | 99.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 45,339 psi | 88% | 3176 fps | 99.7% |
| Somchem S335 | <<locked>> | 84% | 45,455 psi | 88% | 3189 fps | 99.6% |
| Somchem S355 | <<locked>> | 92% | 45,905 psi | 89% | 3284 fps | 96.6% |
| Somchem S365ᴾ | <<locked>> | 100% | 42,989 psi | 83% | 3314 fps | 97.3% |
| Vihtavuori N133 | <<locked>> | 84% | 45,716 psi | 89% | 3186 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 46,296 psi | 90% | 3271 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 44,585 psi | 87% | 3215 fps | 99.3% |
| Vihtavuori N150 | <<locked>> | 92% | 44,005 psi | 85% | 3209 fps | 97.6% |
| Vihtavuori N530 | <<locked>> | 82% | 44,237 psi | 86% | 3215 fps | 97.1% |
| Vihtavuori N540 | <<locked>> | 88% | 45,948 psi | 89% | 3255 fps | 99.2% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 45,295 psi | 88% | 3228 fps | 96.5% |
| Winchester 748 | <<locked>> | 84% | 46,093 psi | 90% | 3320 fps | 98.3% |
| Winchester StaBALL Match | <<locked>> | 86% | 45,687 psi | 89% | 3287 fps | 96.7% |
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% | 43,555 psi | 85% | 3166 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 37,173 psi | 72% | 3064 fps | 99.6% |
| Accurate 2520 | <<locked>> | 80% | 42,337 psi | 82% | 3199 fps | 98.2% |
| Accurate 4064 | <<locked>> | 80% | 34,983 psi | 68% | 3028 fps | 97.2% |
| ADI Benchmark 8208 | <<locked>> | 80% | 41,510 psi | 81% | 3156 fps | 96.2% |
| Alliant AR-Comp | <<locked>> | 80% | 40,553 psi | 79% | 3189 fps | 100% |
| Alliant Reloder- TS 15.5 | 40.6 gr | 86% | 39,900 psi | 77% | 3156 fps | 95.3% |
| Alliant Reloder-17 | <<locked>> | 92% | 42,438 psi | 82% | 3294 fps | 95.3% |
| Bofors RP3 | <<locked>> | 86% | 40,089 psi | 78% | 3169 fps | 95.5% |
| Hodgdon Benchmark | <<locked>> | 80% | 43,424 psi | 84% | 3159 fps | 97.4% |
| Hodgdon BL-C2 | <<locked>> | 80% | 40,001 psi | 78% | 3166 fps | 96.5% |
| Hodgdon H4895 | <<locked>> | 82% | 42,641 psi | 83% | 3215 fps | 95.7% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 40,988 psi | 80% | 3225 fps | 95.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,194 psi | 51% | 1965 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 40,872 psi | 79% | 3153 fps | 95.1% |
| IMR 3031 | <<locked>> | 80% | 38,682 psi | 75% | 3169 fps | 99.3% |
| IMR 8208 XBR | <<locked>> | 80% | 41,510 psi | 81% | 3156 fps | 96.2% |
| Lovex D073.6 | <<locked>> | 80% | 38,609 psi | 75% | 3120 fps | 97.2% |
| Lovex S060 | <<locked>> | 82% | 42,627 psi | 83% | 3133 fps | 95.1% |
| Lovex S062 | <<locked>> | 82% | 37,782 psi | 73% | 3068 fps | 95.1% |
| Norma 201 | <<locked>> | 80% | 39,523 psi | 77% | 3100 fps | 95.7% |
| Norma 202 | <<locked>> | 80% | 39,160 psi | 76% | 3117 fps | 98% |
| Norma 203B | <<locked>> | 86% | 42,366 psi | 82% | 3222 fps | 95% |
| Ramshot Wild Boar | <<locked>> | 82% | 43,482 psi | 84% | 3228 fps | 95.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,324 psi | 51% | 2008 fps | 100% |
| ReloadSwiss RS 60 | 43.3 gr | 86% | 37,159 psi | 72% | 3169 fps | 96% |
| Rottweil R 901 | <<locked>> | 80% | 43,526 psi | 85% | 3182 fps | 98.6% |
| Rottweil R 902 | <<locked>> | 80% | 37,768 psi | 73% | 3045 fps | 95% |
| Rottweil R 903 | 41.8 gr | 88% | 39,943 psi | 78% | 3156 fps | 95.1% |
| Shooters World Match Rifle | <<locked>> | 80% | 38,609 psi | 75% | 3120 fps | 97.2% |
| Shooters World Precision | <<locked>> | 82% | 37,782 psi | 73% | 3068 fps | 95.1% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 43,424 psi | 84% | 3268 fps | 95.2% |
| SNPE Vectan SP 9 | <<locked>> | 84% | 43,439 psi | 84% | 3219 fps | 95.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 40,451 psi | 79% | 3068 fps | 98.3% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 33,446 psi | 65% | 2897 fps | 97.5% |
| Somchem S335 | <<locked>> | 80% | 40,393 psi | 78% | 3074 fps | 98.9% |
| Somchem S355 | <<locked>> | 88% | 40,988 psi | 80% | 3169 fps | 95.2% |
| Somchem S365 | <<locked>> | 96% | 38,101 psi | 74% | 3182 fps | 95.5% |
| Vihtavuori N133 | <<locked>> | 80% | 40,350 psi | 78% | 3071 fps | 99.7% |
| Vihtavuori N135 | <<locked>> | 80% | 36,056 psi | 70% | 3041 fps | 99.4% |
| Vihtavuori N140 | <<locked>> | 80% | 36,956 psi | 72% | 3035 fps | 97.8% |
| Vihtavuori N150 | <<locked>> | 86% | 36,695 psi | 71% | 3035 fps | 95.4% |
| Vihtavuori N530 | <<locked>> | 80% | 41,698 psi | 81% | 3156 fps | 96.4% |
| Vihtavuori N540 | <<locked>> | 80% | 35,911 psi | 70% | 3018 fps | 97% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 42,612 psi | 83% | 3169 fps | 95.6% |
| Winchester 748 | <<locked>> | 80% | 40,393 psi | 78% | 3189 fps | 96.9% |
| Winchester StaBALL Match | <<locked>> | 84% | 42,583 psi | 83% | 3215 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 47 powders for .257 Roberts loaded with the .257 | 75gr | Barnes X. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,386 fps; across all powders the maximum-charge window runs from 2,185 fps to 3,386 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 47 of the 47 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (355 MPa), the top charges use 68–90 %, leaving at least 10 % headroom. The 75.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Hodgdon TrailBoss, ReloadSwiss RS 14, Somchem S365 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, Rottweil R 903 rank at the top here: for .257 Roberts with the .257 | 75gr | Barnes X 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.