Load Specifications
Load data in caliber .257 Roberts with .257 | 100gr | Speer Varmint Hollow Point bullet and 48 powders. The key underlying parameters are shown in the table above.
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>> | 82% | 44,773 psi | 87% | 2864 fps | 100% |
| Accurate 4064 | <<locked>> | 84% | 44,918 psi | 87% | 2907 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 44,193 psi | 86% | 2963 fps | 97.6% |
| ADI AR 2208 | <<locked>> | 86% | 46,528 psi | 90% | 2930 fps | 98.5% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 44,150 psi | 86% | 3015 fps | 98% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 46,267 psi | 90% | 2953 fps | 99.5% |
| Alliant Reloder-15 | <<locked>> | 82% | 43,874 psi | 85% | 2913 fps | 98.1% |
| Alliant Reloder-16 | <<locked>> | 94% | 46,108 psi | 90% | 3031 fps | 98.3% |
| Alliant Reloder-17 | <<locked>> | 90% | 46,311 psi | 90% | 3058 fps | 99.4% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 39,842 psi | 77% | 2913 fps | 98.2% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 44,860 psi | 87% | 3084 fps | 97.5% |
| Bofors RP3 | <<locked>> | 86% | 46,267 psi | 90% | 2959 fps | 99.5% |
| Hodgdon H380 | <<locked>> | 84% | 44,251 psi | 86% | 2910 fps | 97% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 45,469 psi | 88% | 2959 fps | 99.2% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 44,686 psi | 87% | 2963 fps | 99.4% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,607 psi | 69% | 1926 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 45,774 psi | 89% | 2907 fps | 98.5% |
| IMR 4831 | <<locked>> | 94% | 45,295 psi | 88% | 2966 fps | 97.9% |
| IMR 4895 | <<locked>> | 82% | 44,947 psi | 87% | 2946 fps | 98.8% |
| Lovex S062 | <<locked>> | 84% | 45,774 psi | 89% | 2913 fps | 99.6% |
| Lovex S065 | <<locked>> | 90% | 45,411 psi | 88% | 2904 fps | 96.4% |
| Norma 203B | <<locked>> | 84% | 45,919 psi | 89% | 2953 fps | 98.9% |
| Norma URP | <<locked>> | 92% | 43,888 psi | 85% | 2953 fps | 97.4% |
| Ramshot Big Game | <<locked>> | 84% | 46,093 psi | 90% | 2976 fps | 98.8% |
| Ramshot Hunter | <<locked>> | 94% | 45,759 psi | 89% | 2995 fps | 96.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,027 psi | 70% | 1969 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 46,267 psi | 90% | 3025 fps | 98.5% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 46,108 psi | 90% | 3064 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 43,874 psi | 85% | 2976 fps | 97.2% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 43,801 psi | 85% | 2992 fps | 96.6% |
| Rottweil R 902 | <<locked>> | 82% | 44,831 psi | 87% | 2874 fps | 99.5% |
| Rottweil R 903 | <<locked>> | 88% | 46,499 psi | 90% | 2956 fps | 99.4% |
| Shooters World Long Rifle | <<locked>> | 90% | 45,411 psi | 88% | 2904 fps | 96.4% |
| Shooters World Precision | <<locked>> | 84% | 45,774 psi | 89% | 2913 fps | 99.6% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 44,672 psi | 87% | 2956 fps | 98.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 45,847 psi | 89% | 2828 fps | 100% |
| Somchem S355 | <<locked>> | 86% | 44,193 psi | 86% | 2904 fps | 98.9% |
| Somchem S365 | <<locked>> | 96% | 45,005 psi | 87% | 3022 fps | 99.9% |
| Vihtavuori N135 | <<locked>> | 82% | 44,483 psi | 86% | 2858 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 45,063 psi | 88% | 2864 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 45,136 psi | 88% | 2887 fps | 99.8% |
| Vihtavuori N160 | <<locked>> | 92% | 45,992 psi | 89% | 2956 fps | 97.8% |
| Vihtavuori N540 | <<locked>> | 84% | 46,499 psi | 90% | 2907 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 45,092 psi | 88% | 2953 fps | 97.4% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 43,729 psi | 85% | 2995 fps | 98.1% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 46,166 psi | 90% | 2936 fps | 99.4% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 35,708 psi | 69% | 2900 fps | 97.8% |
| Winchester StaBALL Match | <<locked>> | 82% | 46,412 psi | 90% | 2953 fps | 99.3% |
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 80% | 42,018 psi | 82% | 2815 fps | 100% |
| Accurate 4064 | <<locked>> | 80% | 39,697 psi | 77% | 2802 fps | 99.9% |
| Accurate 4350 | <<locked>> | 86% | 35,795 psi | 70% | 2772 fps | 95% |
| ADI AR 2208 | <<locked>> | 80% | 38,609 psi | 75% | 2759 fps | 96.6% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 41,249 psi | 80% | 2946 fps | 97.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 38,305 psi | 74% | 2782 fps | 98.1% |
| Alliant Reloder-15 | <<locked>> | 80% | 41,046 psi | 80% | 2851 fps | 97.4% |
| Alliant Reloder-16 | <<locked>> | 86% | 35,824 psi | 70% | 2782 fps | 95% |
| Alliant Reloder-17 | <<locked>> | 80% | 33,054 psi | 64% | 2736 fps | 95.8% |
| Alliant Reloder-23 | <<locked>> | 94% | 33,127 psi | 64% | 2733 fps | 95.7% |
| Alliant Reloder-26 | <<locked>> | 96% | 38,783 psi | 75% | 2940 fps | 95.4% |
| Bofors RP3 | <<locked>> | 80% | 37,898 psi | 74% | 2782 fps | 98.1% |
| Hodgdon H380 | <<locked>> | 80% | 38,638 psi | 75% | 2782 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 32,851 psi | 64% | 2671 fps | 95.9% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 41,785 psi | 81% | 2900 fps | 98.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,382 psi | 51% | 1719 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 40,538 psi | 79% | 2799 fps | 97.4% |
| IMR 4831 | <<locked>> | 88% | 37,057 psi | 72% | 2785 fps | 95.6% |
| IMR 4895 | <<locked>> | 80% | 42,032 psi | 82% | 2884 fps | 98.2% |
| Lovex S062 | <<locked>> | 80% | 40,292 psi | 78% | 2799 fps | 98.8% |
| Lovex S065 | <<locked>> | 88% | 42,540 psi | 83% | 2844 fps | 95.7% |
| Norma 203B | <<locked>> | 80% | 40,408 psi | 78% | 2838 fps | 97.8% |
| Norma URP | <<locked>> | 88% | 38,479 psi | 75% | 2835 fps | 95.8% |
| Ramshot Big Game | <<locked>> | 80% | 39,987 psi | 78% | 2848 fps | 97.5% |
| Ramshot Hunter | <<locked>> | 92% | 42,830 psi | 83% | 2933 fps | 95.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,847 psi | 52% | 1762 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 43,410 psi | 84% | 2966 fps | 97.9% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 35,186 psi | 68% | 2812 fps | 98.9% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 38,145 psi | 74% | 2851 fps | 95.5% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 41,017 psi | 80% | 2927 fps | 95.6% |
| Rottweil R 902 | <<locked>> | 80% | 42,221 psi | 82% | 2822 fps | 99.1% |
| Rottweil R 903 | <<locked>> | 80% | 35,737 psi | 69% | 2726 fps | 97.2% |
| Shooters World Long Rifle | <<locked>> | 88% | 42,540 psi | 83% | 2844 fps | 95.7% |
| Shooters World Precision | <<locked>> | 80% | 40,292 psi | 78% | 2799 fps | 98.8% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 36,724 psi | 71% | 2776 fps | 96.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 38,029 psi | 74% | 2680 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 36,564 psi | 71% | 2733 fps | 97.2% |
| Somchem S365 | <<locked>> | 82% | 28,195 psi | 55% | 2592 fps | 95.2% |
| Vihtavuori N135 | <<locked>> | 80% | 41,727 psi | 81% | 2808 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 42,409 psi | 82% | 2815 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 34,737 psi | 67% | 2664 fps | 98% |
| Vihtavuori N160 | <<locked>> | 86% | 37,652 psi | 73% | 2779 fps | 95.5% |
| Vihtavuori N540 | <<locked>> | 80% | 40,741 psi | 79% | 2795 fps | 99.9% |
| Vihtavuori N550 | <<locked>> | 86% | 37,144 psi | 72% | 2779 fps | 95% |
| Vihtavuori N555 | <<locked>> | 94% | 35,882 psi | 70% | 2818 fps | 95.8% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 30,748 psi | 60% | 2572 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 96% | 31,285 psi | 61% | 2749 fps | 95.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 43,395 psi | 84% | 2890 fps | 98.9% |
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 48 powders for .257 Roberts loaded with the .257 | 100gr | Speer Varmint Hollow Point. Alliant Reloder-26 delivers the highest muzzle velocity at 3,084 fps; across all powders the maximum-charge window runs from 1,926 fps to 3,084 fps. Alliant Reloder-23 gives the best case fill at 100 %, and 48 of the 48 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (355 MPa), the top charges use 69–90 %, leaving at least 10 % headroom. The 100.0 gr projectile in 0.257" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Alliant Reloder-23, Alliant Reloder-26, 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. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.