Load Specifications
Load data in caliber .257 Roberts with .257 | 80gr | Impala LWHV LS bullet and 53 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 Alliant Reloder- TS 15.5.
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% | 46,398 psi | 90% | 3123 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 44,831 psi | 87% | 3140 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 45,571 psi | 89% | 3176 fps | 99% |
| Accurate 4064 | <<locked>> | 88% | 44,657 psi | 87% | 3169 fps | 99.5% |
| ADI AR 2206H | <<locked>> | 84% | 45,295 psi | 88% | 3173 fps | 96.3% |
| ADI Benchmark 8208 | <<locked>> | 82% | 44,541 psi | 87% | 3133 fps | 97.4% |
| Alliant AR-Comp | <<locked>> | 84% | 46,470 psi | 90% | 3205 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 45,484 psi | 88% | 3192 fps | 97.4% |
| Alliant Reloder-15 | <<locked>> | 88% | 45,934 psi | 89% | 3205 fps | 95.9% |
| Alliant Reloder-17 | <<locked>> | 94% | 45,237 psi | 88% | 3274 fps | 96.7% |
| Bofors RP3 | <<locked>> | 90% | 45,629 psi | 89% | 3205 fps | 97.5% |
| Hodgdon Benchmark | <<locked>> | 82% | 46,499 psi | 90% | 3130 fps | 98.4% |
| Hodgdon BL-C2 | <<locked>> | 84% | 45,934 psi | 89% | 3209 fps | 98.3% |
| Hodgdon H4895 | <<locked>> | 84% | 45,585 psi | 89% | 3189 fps | 97% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 44,063 psi | 86% | 3169 fps | 96.4% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 46,543 psi | 90% | 3261 fps | 97.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,128 psi | 68% | 2106 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 46,485 psi | 90% | 3189 fps | 97.1% |
| IMR 3031 | <<locked>> | 84% | 44,469 psi | 86% | 3202 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 45,397 psi | 88% | 3146 fps | 95.8% |
| IMR 4895 | <<locked>> | 86% | 44,280 psi | 86% | 3186 fps | 96.1% |
| IMR 8208 XBR | <<locked>> | 82% | 44,541 psi | 87% | 3133 fps | 97.4% |
| Lovex D073.6 | <<locked>> | 84% | 44,338 psi | 86% | 3159 fps | 98.8% |
| Lovex S060 | <<locked>> | 84% | 45,382 psi | 88% | 3104 fps | 96.4% |
| Lovex S062 | <<locked>> | 88% | 45,455 psi | 88% | 3159 fps | 97.7% |
| Norma 201 | <<locked>> | 84% | 44,585 psi | 87% | 3127 fps | 97.5% |
| Norma 202 | <<locked>> | 84% | 44,295 psi | 86% | 3140 fps | 99.3% |
| Norma 203B | <<locked>> | 88% | 45,223 psi | 88% | 3192 fps | 96.3% |
| Ramshot Big Game | <<locked>> | 88% | 45,034 psi | 87% | 3205 fps | 96% |
| Ramshot Wild Boar | <<locked>> | 84% | 46,470 psi | 90% | 3202 fps | 96.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,505 psi | 69% | 2156 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 45,034 psi | 87% | 3291 fps | 98.9% |
| Rottweil R 901 | <<locked>> | 82% | 46,470 psi | 90% | 3150 fps | 99.3% |
| Rottweil R 902 | <<locked>> | 86% | 45,266 psi | 88% | 3133 fps | 97.6% |
| Rottweil R 903 | <<locked>> | 92% | 45,484 psi | 88% | 3192 fps | 97.1% |
| Shooters World Match Rifle | <<locked>> | 84% | 44,338 psi | 86% | 3159 fps | 98.8% |
| Shooters World Precision | <<locked>> | 88% | 45,455 psi | 88% | 3159 fps | 97.7% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 46,369 psi | 90% | 3189 fps | 96.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 46,064 psi | 89% | 3091 fps | 99.4% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 45,513 psi | 88% | 3084 fps | 99.8% |
| Somchem S335 | <<locked>> | 84% | 45,513 psi | 88% | 3091 fps | 99.7% |
| Somchem S341 | <<locked>> | 84% | 45,005 psi | 87% | 3143 fps | 96.1% |
| Somchem S355 | <<locked>> | 92% | 46,064 psi | 89% | 3192 fps | 97.1% |
| Somchem S365ᴾ | <<locked>> | 100% | 43,033 psi | 84% | 3225 fps | 97.7% |
| Vihtavuori N133 | <<locked>> | 84% | 45,934 psi | 89% | 3091 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 46,456 psi | 90% | 3176 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 44,831 psi | 87% | 3123 fps | 99.5% |
| Vihtavuori N150 | <<locked>> | 92% | 44,266 psi | 86% | 3120 fps | 98% |
| Vihtavuori N530 | <<locked>> | 82% | 44,657 psi | 87% | 3127 fps | 97.5% |
| Vihtavuori N540 | <<locked>> | 88% | 46,093 psi | 90% | 3163 fps | 99.4% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 45,571 psi | 89% | 3146 fps | 97% |
| Winchester 748 | <<locked>> | 84% | 46,485 psi | 90% | 3232 fps | 98.6% |
| Winchester StaBALL Match | <<locked>> | 86% | 45,876 psi | 89% | 3196 fps | 97.1% |
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% | 43,598 psi | 85% | 3071 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 37,318 psi | 72% | 2976 fps | 99.7% |
| Accurate 2520 | <<locked>> | 80% | 42,598 psi | 83% | 3110 fps | 98.5% |
| Accurate 4064 | <<locked>> | 80% | 35,201 psi | 68% | 2943 fps | 97.7% |
| ADI AR 2206H | <<locked>> | 82% | 42,627 psi | 83% | 3114 fps | 95.5% |
| ADI Benchmark 8208 | <<locked>> | 80% | 41,756 psi | 81% | 3068 fps | 96.7% |
| Alliant AR-Comp | <<locked>> | 80% | 40,727 psi | 79% | 3094 fps | 100% |
| Alliant Reloder- TS 15.5 | 38.1 gr | 84% | 37,724 psi | 73% | 3012 fps | 95.1% |
| Alliant Reloder-15 | <<locked>> | 86% | 43,337 psi | 84% | 3146 fps | 95.1% |
| Alliant Reloder-17 | 44.5 gr | 92% | 42,380 psi | 82% | 3205 fps | 95.8% |
| Bofors RP3 | <<locked>> | 84% | 37,739 psi | 73% | 3018 fps | 95.2% |
| Hodgdon Benchmark | <<locked>> | 80% | 43,888 psi | 85% | 3074 fps | 97.8% |
| Hodgdon BL-C2 | <<locked>> | 80% | 40,234 psi | 78% | 3081 fps | 97% |
| Hodgdon H4895 | <<locked>> | 80% | 40,263 psi | 78% | 3061 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 41,495 psi | 81% | 3110 fps | 95.6% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 38,450 psi | 75% | 3068 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,034 psi | 51% | 1883 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 40,988 psi | 80% | 3064 fps | 95.6% |
| IMR 3031 | <<locked>> | 80% | 39,088 psi | 76% | 3084 fps | 99.5% |
| IMR 4064 | <<locked>> | 86% | 42,743 psi | 83% | 3087 fps | 95% |
| IMR 4895 | <<locked>> | 84% | 41,669 psi | 81% | 3127 fps | 95.3% |
| IMR 8208 XBR | <<locked>> | 80% | 41,756 psi | 81% | 3068 fps | 96.7% |
| Lovex D073.6 | <<locked>> | 80% | 39,015 psi | 76% | 3038 fps | 97.7% |
| Lovex S060 | <<locked>> | 82% | 42,844 psi | 83% | 3045 fps | 95.7% |
| Lovex S062 | <<locked>> | 82% | 38,000 psi | 74% | 2986 fps | 95.7% |
| Norma 201 | <<locked>> | 80% | 39,639 psi | 77% | 3012 fps | 96.2% |
| Norma 202 | <<locked>> | 80% | 39,291 psi | 76% | 3028 fps | 98.4% |
| Norma 203B | <<locked>> | 86% | 42,627 psi | 83% | 3133 fps | 95.6% |
| Ramshot Big Game | <<locked>> | 86% | 42,192 psi | 82% | 3136 fps | 95.1% |
| Ramshot Wild Boar | <<locked>> | 80% | 41,046 psi | 80% | 3077 fps | 95% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,440 psi | 51% | 1929 fps | 100% |
| ReloadSwiss RS 60 | 40.7 gr | 84% | 35,230 psi | 68% | 3022 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 43,845 psi | 85% | 3094 fps | 99% |
| Rottweil R 902 | <<locked>> | 80% | 37,898 psi | 74% | 2959 fps | 95.6% |
| Rottweil R 903 | <<locked>> | 88% | 40,234 psi | 78% | 3074 fps | 95.7% |
| Shooters World Match Rifle | <<locked>> | 80% | 39,015 psi | 76% | 3038 fps | 97.7% |
| Shooters World Precision | <<locked>> | 82% | 38,000 psi | 74% | 2986 fps | 95.7% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 40,988 psi | 80% | 3068 fps | 95% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 40,756 psi | 79% | 2979 fps | 98.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 33,721 psi | 65% | 2815 fps | 97.9% |
| Somchem S335 | <<locked>> | 80% | 40,509 psi | 79% | 2986 fps | 99.2% |
| Somchem S341 | <<locked>> | 82% | 42,119 psi | 82% | 3077 fps | 95.3% |
| Somchem S355 | <<locked>> | 88% | 40,944 psi | 80% | 3077 fps | 95.6% |
| Somchem S365 | <<locked>> | 94% | 36,085 psi | 70% | 3041 fps | 95.2% |
| Vihtavuori N133 | <<locked>> | 80% | 40,698 psi | 79% | 2986 fps | 99.9% |
| Vihtavuori N135 | <<locked>> | 80% | 36,405 psi | 71% | 2959 fps | 99.6% |
| Vihtavuori N140 | <<locked>> | 80% | 37,130 psi | 72% | 2949 fps | 98.2% |
| Vihtavuori N150 | <<locked>> | 84% | 34,737 psi | 67% | 2894 fps | 95.2% |
| Vihtavuori N530 | <<locked>> | 80% | 41,727 psi | 81% | 3061 fps | 96.8% |
| Vihtavuori N540 | <<locked>> | 80% | 35,969 psi | 70% | 2930 fps | 97.4% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 40,147 psi | 78% | 3022 fps | 95.2% |
| Winchester 748 | <<locked>> | 80% | 40,843 psi | 79% | 3107 fps | 97.4% |
| Winchester StaBALL Match | <<locked>> | 82% | 40,219 psi | 78% | 3068 fps | 95.5% |
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 78 powders for .257 Roberts loaded with the .257 | 80gr | Impala LWHV LS. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,291 fps; across all powders the maximum-charge window runs from 2,106 fps to 3,291 fps. Alliant Reloder-23 gives the best case fill at 100 %, and 78 of the 78 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (355 MPa), the top charges use 67–90 %, 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 Hybrid 100V, Hodgdon TrailBoss 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, Alliant Reloder- TS 15.5 rank at the top here: for .257 Roberts 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.