Load Specifications
Load data in caliber .257 Roberts with .257 | 88gr | Osprey Virtus bullet and 64 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 Norma 203B.
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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 82% | 45,397 psi | 88% | 3012 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 45,687 psi | 89% | 3061 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 44,875 psi | 87% | 3071 fps | 99.6% |
| Accurate 4064 | <<locked>> | 90% | 46,137 psi | 90% | 3107 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 45,368 psi | 88% | 3146 fps | 96.3% |
| ADI AR 2206H | <<locked>> | 84% | 44,933 psi | 87% | 3077 fps | 97.4% |
| ADI AR 2208 | <<locked>> | 90% | 45,890 psi | 89% | 3074 fps | 97% |
| ADI Benchmark 8208 | <<locked>> | 82% | 44,150 psi | 86% | 3035 fps | 98.4% |
| Alliant AR-Comp | <<locked>> | 82% | 43,758 psi | 85% | 3045 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 86% | 44,005 psi | 85% | 3163 fps | 96.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 45,266 psi | 88% | 3100 fps | 98.4% |
| Alliant Reloder-15 | <<locked>> | 88% | 45,687 psi | 89% | 3114 fps | 97.1% |
| Alliant Reloder-16 | <<locked>> | 98% | 45,165 psi | 88% | 3159 fps | 96.4% |
| Alliant Reloder-17 | <<locked>> | 94% | 45,672 psi | 89% | 3202 fps | 98.2% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 44,309 psi | 86% | 3074 fps | 96.2% |
| Bofors RP3 | <<locked>> | 90% | 45,208 psi | 88% | 3107 fps | 98.5% |
| Hodgdon Benchmark | <<locked>> | 82% | 46,151 psi | 90% | 3031 fps | 99.1% |
| Hodgdon BL-C2 | <<locked>> | 84% | 45,629 psi | 89% | 3107 fps | 99.1% |
| Hodgdon H380 | <<locked>> | 90% | 46,427 psi | 90% | 3110 fps | 96% |
| Hodgdon H4895 | <<locked>> | 84% | 45,339 psi | 88% | 3094 fps | 98.1% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 44,092 psi | 86% | 3091 fps | 97.8% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 43,830 psi | 85% | 3110 fps | 98.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,505 psi | 67% | 2021 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 43,497 psi | 84% | 3035 fps | 97.6% |
| IMR 3031 | <<locked>> | 84% | 44,280 psi | 86% | 3094 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 45,310 psi | 88% | 3058 fps | 97.1% |
| IMR 4831ᴾ | <<locked>> | 100% | 46,412 psi | 90% | 3146 fps | 96.7% |
| IMR 4895 | <<locked>> | 86% | 43,976 psi | 85% | 3091 fps | 97.3% |
| IMR 8208 XBR | <<locked>> | 82% | 44,150 psi | 86% | 3035 fps | 98.4% |
| Lovex D073.6 | <<locked>> | 86% | 46,528 psi | 90% | 3110 fps | 99.7% |
| Lovex S060 | <<locked>> | 84% | 45,310 psi | 88% | 3015 fps | 97.6% |
| Lovex S062 | <<locked>> | 88% | 44,831 psi | 87% | 3058 fps | 98.6% |
| Norma 201 | <<locked>> | 86% | 46,528 psi | 90% | 3084 fps | 98.9% |
| Norma 202 | <<locked>> | 84% | 44,019 psi | 85% | 3041 fps | 99.8% |
| Norma 203B | <<locked>> | 88% | 44,962 psi | 87% | 3097 fps | 97.5% |
| Norma URP | <<locked>> | 98% | 45,440 psi | 88% | 3143 fps | 96.2% |
| Ramshot Big Game | <<locked>> | 88% | 45,281 psi | 88% | 3120 fps | 97.4% |
| Ramshot Wild Boar | <<locked>> | 82% | 43,627 psi | 85% | 3054 fps | 97.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,751 psi | 67% | 2067 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 45,107 psi | 88% | 3169 fps | 96.9% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 45,484 psi | 88% | 3215 fps | 99.7% |
| Rottweil R 901 | <<locked>> | 82% | 44,715 psi | 87% | 3028 fps | 99.7% |
| Rottweil R 902 | <<locked>> | 86% | 43,976 psi | 85% | 3022 fps | 98.4% |
| Rottweil R 903 | <<locked>> | 92% | 45,092 psi | 88% | 3097 fps | 98.2% |
| Shooters World Match Rifle | <<locked>> | 86% | 46,528 psi | 90% | 3110 fps | 99.7% |
| Shooters World Precision | <<locked>> | 88% | 44,831 psi | 87% | 3058 fps | 98.6% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 43,888 psi | 85% | 3100 fps | 97.2% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 46,325 psi | 90% | 3097 fps | 97.7% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 45,527 psi | 88% | 2992 fps | 99.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 45,571 psi | 89% | 2992 fps | 100% |
| Somchem S335 | <<locked>> | 84% | 44,918 psi | 87% | 2989 fps | 100% |
| Somchem S341 | <<locked>> | 84% | 45,165 psi | 88% | 3061 fps | 97.4% |
| Somchem S355 | <<locked>> | 92% | 45,905 psi | 89% | 3104 fps | 98.2% |
| Somchem S365ᴾ | <<locked>> | 100% | 43,265 psi | 84% | 3146 fps | 98.9% |
| Vihtavuori N133 | <<locked>> | 84% | 45,701 psi | 89% | 2989 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 46,267 psi | 90% | 3071 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 44,657 psi | 87% | 3025 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 92% | 44,222 psi | 86% | 3031 fps | 98.9% |
| Vihtavuori N160 | <<locked>> | 96% | 44,585 psi | 87% | 3084 fps | 95.8% |
| Vihtavuori N530 | <<locked>> | 82% | 44,135 psi | 86% | 3028 fps | 98.5% |
| Vihtavuori N540 | <<locked>> | 88% | 46,108 psi | 90% | 3068 fps | 99.9% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 45,759 psi | 89% | 3074 fps | 98.3% |
| Winchester 748 | <<locked>> | 82% | 43,439 psi | 84% | 3074 fps | 99% |
| Winchester StaBALL Match | <<locked>> | 86% | 45,847 psi | 89% | 3104 fps | 98.2% |
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% | 42,540 psi | 83% | 2956 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 34,650 psi | 67% | 2831 fps | 99.9% |
| Accurate 2520 | <<locked>> | 80% | 41,742 psi | 81% | 3005 fps | 99.2% |
| Accurate 4064 | <<locked>> | 80% | 32,793 psi | 64% | 2805 fps | 98.1% |
| Accurate 4350 | <<locked>> | 96% | 41,959 psi | 81% | 3074 fps | 95.3% |
| ADI AR 2206H | <<locked>> | 80% | 39,363 psi | 76% | 2953 fps | 95.9% |
| ADI AR 2208 | <<locked>> | 86% | 40,524 psi | 79% | 2959 fps | 95.5% |
| ADI Benchmark 8208 | <<locked>> | 80% | 41,481 psi | 81% | 2976 fps | 97.8% |
| Alliant AR-Comp | <<locked>> | 80% | 40,495 psi | 79% | 2986 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 84% | 40,785 psi | 79% | 3084 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 34,809 psi | 68% | 2854 fps | 95.4% |
| Alliant Reloder-15 | <<locked>> | 84% | 40,277 psi | 78% | 2992 fps | 95.6% |
| Alliant Reloder-16 | <<locked>> | 96% | 42,148 psi | 82% | 3091 fps | 95.4% |
| Alliant Reloder-17 | 43.6 gr | 88% | 37,028 psi | 72% | 2989 fps | 95.4% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 41,350 psi | 80% | 3009 fps | 95.3% |
| Bofors RP3 | <<locked>> | 82% | 33,939 psi | 66% | 2841 fps | 95.2% |
| Hodgdon Benchmark | <<locked>> | 80% | 43,424 psi | 84% | 2979 fps | 98.7% |
| Hodgdon BL-C2 | <<locked>> | 80% | 39,624 psi | 77% | 2979 fps | 97.9% |
| Hodgdon H380 | <<locked>> | 88% | 43,555 psi | 85% | 3051 fps | 95.1% |
| Hodgdon H4895 | <<locked>> | 80% | 39,697 psi | 77% | 2966 fps | 96.6% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 36,071 psi | 70% | 2900 fps | 95.2% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 35,679 psi | 69% | 2913 fps | 95.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,469 psi | 49% | 1808 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 38,058 psi | 74% | 2910 fps | 96.1% |
| IMR 3031 | <<locked>> | 80% | 38,653 psi | 75% | 2979 fps | 99.9% |
| IMR 4064 | <<locked>> | 84% | 39,900 psi | 77% | 2936 fps | 95.6% |
| IMR 4831 | <<locked>> | 98% | 43,453 psi | 84% | 3087 fps | 95.9% |
| IMR 4895 | <<locked>> | 82% | 38,435 psi | 75% | 2959 fps | 95.7% |
| IMR 8208 XBR | <<locked>> | 80% | 41,481 psi | 81% | 2976 fps | 97.8% |
| Lovex D073.6 | <<locked>> | 80% | 37,681 psi | 73% | 2923 fps | 98.4% |
| Lovex S060 | <<locked>> | 80% | 39,798 psi | 77% | 2894 fps | 96.1% |
| Lovex S062 | <<locked>> | 80% | 34,505 psi | 67% | 2815 fps | 95.8% |
| Norma 201 | <<locked>> | 80% | 38,189 psi | 74% | 2900 fps | 97% |
| Norma 202 | <<locked>> | 80% | 38,696 psi | 75% | 2927 fps | 99.1% |
| Norma 203B | 38.7 gr | 82% | 36,854 psi | 72% | 2910 fps | 95.1% |
| Norma URP | <<locked>> | 96% | 42,264 psi | 82% | 3077 fps | 95.3% |
| Ramshot Big Game | <<locked>> | 84% | 39,102 psi | 76% | 2982 fps | 95.6% |
| Ramshot Wild Boar | <<locked>> | 80% | 40,727 psi | 79% | 2989 fps | 96.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,788 psi | 50% | 1854 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 39,160 psi | 76% | 3035 fps | 95.1% |
| ReloadSwiss RS 60 | 40.6 gr | 82% | 32,126 psi | 62% | 2858 fps | 95.9% |
| Rottweil R 901 | <<locked>> | 80% | 41,974 psi | 82% | 2972 fps | 99.4% |
| Rottweil R 902 | <<locked>> | 80% | 36,361 psi | 71% | 2844 fps | 96.4% |
| Rottweil R 903 | <<locked>> | 86% | 36,724 psi | 71% | 2910 fps | 95.9% |
| Shooters World Match Rifle | <<locked>> | 80% | 37,681 psi | 73% | 2923 fps | 98.4% |
| Shooters World Precision | <<locked>> | 80% | 34,505 psi | 67% | 2815 fps | 95.8% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 38,130 psi | 74% | 2966 fps | 95.4% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 37,913 psi | 74% | 2910 fps | 95.4% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 39,972 psi | 78% | 2877 fps | 99.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 32,866 psi | 64% | 2717 fps | 98.6% |
| Somchem S335 | <<locked>> | 80% | 39,407 psi | 77% | 2877 fps | 99.6% |
| Somchem S341 | <<locked>> | 80% | 39,030 psi | 76% | 2927 fps | 95.7% |
| Somchem S355 | <<locked>> | 84% | 35,317 psi | 69% | 2858 fps | 95.1% |
| Somchem S365 | <<locked>> | 92% | 32,938 psi | 64% | 2881 fps | 95.6% |
| Vihtavuori N133 | <<locked>> | 80% | 40,190 psi | 78% | 2884 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 35,418 psi | 69% | 2844 fps | 99.9% |
| Vihtavuori N140 | <<locked>> | 80% | 36,593 psi | 71% | 2851 fps | 99% |
| Vihtavuori N150 | <<locked>> | 82% | 31,444 psi | 61% | 2730 fps | 95.2% |
| Vihtavuori N160 | <<locked>> | 94% | 41,771 psi | 81% | 3022 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 41,379 psi | 80% | 2969 fps | 97.9% |
| Vihtavuori N540 | <<locked>> | 80% | 35,114 psi | 68% | 2828 fps | 98.2% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 37,115 psi | 72% | 2877 fps | 95.8% |
| Winchester 748 | <<locked>> | 80% | 40,422 psi | 79% | 3005 fps | 98.4% |
| Winchester StaBALL Match | <<locked>> | 80% | 37,101 psi | 72% | 2907 fps | 95.9% |
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 64 powders for .257 Roberts loaded with the .257 | 88gr | Osprey Virtus. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,215 fps; across all powders the maximum-charge window runs from 2,021 fps to 3,215 fps. Hodgdon Hybrid 100V gives the best case fill at 100 %, and 64 of the 64 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 88.0 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, Norma 203B rank at the top here: for .257 Roberts with the .257 | 88gr | Osprey Virtus 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.