Load Specifications
Load data in caliber .257 Roberts with .257 | 115gr | Nosler Ballistic Silver Tip bullet and 51 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are IMR 4350, Alliant Reloder-26 and Alliant Reloder-16.
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 3100ᴾ | <<locked>> | 100% | 44,005 psi | 85% | 2743 fps | 97% |
| Accurate 4064 | <<locked>> | 82% | 44,135 psi | 86% | 2690 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 46,572 psi | 90% | 2812 fps | 98.9% |
| ADI AR 2208 | <<locked>> | 84% | 45,295 psi | 88% | 2710 fps | 99% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 46,325 psi | 90% | 2864 fps | 99.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 45,237 psi | 88% | 2733 fps | 99.8% |
| Alliant Reloder-15 | <<locked>> | 82% | 45,469 psi | 88% | 2746 fps | 99.2% |
| Alliant Reloder-16 | <<locked>> | 92% | 45,150 psi | 88% | 2818 fps | 99% |
| Alliant Reloder-17 | <<locked>> | 88% | 45,310 psi | 88% | 2841 fps | 99.8% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 41,684 psi | 81% | 2769 fps | 99.4% |
| Alliant Reloder-26 | <<locked>> | 98% | 43,642 psi | 85% | 2877 fps | 98.3% |
| Bofors RP3 | <<locked>> | 84% | 45,571 psi | 89% | 2749 fps | 99.9% |
| Hodgdon H380 | <<locked>> | 84% | 46,267 psi | 90% | 2756 fps | 98.5% |
| Hodgdon H414 | <<locked>> | 90% | 45,861 psi | 89% | 2802 fps | 96.5% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 44,701 psi | 87% | 2753 fps | 99.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,665 psi | 69% | 1772 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 44,976 psi | 87% | 2697 fps | 99.1% |
| IMR 4350 | <<locked>> | 92% | 46,021 psi | 89% | 2740 fps | 95.8% |
| IMR 4451 Enduron | <<locked>> | 86% | 44,773 psi | 87% | 2697 fps | 95.9% |
| IMR 4831 | <<locked>> | 92% | 44,353 psi | 86% | 2756 fps | 98.6% |
| Lovex S062 | <<locked>> | 82% | 44,715 psi | 87% | 2694 fps | 99.9% |
| Lovex S065 | <<locked>> | 88% | 44,396 psi | 86% | 2694 fps | 97.3% |
| Lovex S070 | <<locked>> | 90% | 44,947 psi | 87% | 2723 fps | 96.4% |
| Norma 203B | <<locked>> | 82% | 44,846 psi | 87% | 2736 fps | 99.4% |
| Norma MRPᴾ | <<locked>> | 100% | 46,543 psi | 90% | 2890 fps | 96.4% |
| Norma URP | <<locked>> | 92% | 45,934 psi | 89% | 2802 fps | 98.8% |
| Ramshot Big Game | <<locked>> | 82% | 44,976 psi | 87% | 2759 fps | 99.3% |
| Ramshot Hunter | <<locked>> | 92% | 44,730 psi | 87% | 2789 fps | 97.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,216 psi | 70% | 1814 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 46,528 psi | 90% | 2736 fps | 97.1% |
| ReloadSwiss RS 60 | <<locked>> | 86% | 44,947 psi | 87% | 2844 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 45,934 psi | 89% | 2825 fps | 98.6% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 45,687 psi | 89% | 2848 fps | 98.3% |
| Rottweil R 903 | <<locked>> | 86% | 45,440 psi | 88% | 2740 fps | 99.8% |
| Shooters World Long Rifle | <<locked>> | 88% | 44,396 psi | 86% | 2694 fps | 97.3% |
| Shooters World Precision | <<locked>> | 82% | 44,715 psi | 87% | 2694 fps | 99.9% |
| Shooters World SW4350 | <<locked>> | 90% | 44,947 psi | 87% | 2723 fps | 96.4% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 43,874 psi | 85% | 2743 fps | 99.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 44,889 psi | 87% | 2615 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 43,787 psi | 85% | 2638 fps | 95.8% |
| Somchem S355 | <<locked>> | 86% | 46,021 psi | 89% | 2743 fps | 99.7% |
| Somchem S365 | <<locked>> | 94% | 44,048 psi | 86% | 2805 fps | 100% |
| Vihtavuori N135 | <<locked>> | 82% | 46,398 psi | 90% | 2684 fps | 100% |
| Vihtavuori N150 | <<locked>> | 86% | 43,990 psi | 85% | 2674 fps | 100% |
| Vihtavuori N160 | <<locked>> | 90% | 45,136 psi | 88% | 2746 fps | 98.5% |
| Vihtavuori N540 | <<locked>> | 82% | 45,194 psi | 88% | 2687 fps | 100% |
| Vihtavuori N550 | <<locked>> | 90% | 44,150 psi | 86% | 2746 fps | 98.2% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 46,122 psi | 90% | 2848 fps | 99.3% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 44,628 psi | 87% | 2720 fps | 99.8% |
| Winchester 760 | <<locked>> | 90% | 46,195 psi | 90% | 2805 fps | 96.5% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 37,246 psi | 72% | 2779 fps | 99.5% |
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 3100 | <<locked>> | 96% | 38,377 psi | 75% | 2631 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 41,350 psi | 80% | 2638 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 32,735 psi | 64% | 2520 fps | 95.2% |
| ADI AR 2208 | <<locked>> | 80% | 40,132 psi | 78% | 2608 fps | 98.1% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 43,134 psi | 84% | 2799 fps | 98.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 39,755 psi | 77% | 2628 fps | 99.2% |
| Alliant Reloder-15 | <<locked>> | 80% | 42,670 psi | 83% | 2694 fps | 98.7% |
| Alliant Reloder-16 | 36.1 gr | 82% | 33,054 psi | 64% | 2536 fps | 95.4% |
| Alliant Reloder-17 | <<locked>> | 80% | 34,534 psi | 67% | 2602 fps | 97.8% |
| Alliant Reloder-23 | <<locked>> | 88% | 28,747 psi | 56% | 2441 fps | 95.1% |
| Alliant Reloder-26 | 44.7 gr | 92% | 35,404 psi | 69% | 2680 fps | 95.5% |
| Bofors RP3 | <<locked>> | 80% | 39,653 psi | 77% | 2635 fps | 99.3% |
| Hodgdon H380 | <<locked>> | 80% | 40,350 psi | 78% | 2638 fps | 97.2% |
| Hodgdon H414 | <<locked>> | 88% | 42,989 psi | 83% | 2743 fps | 95.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 28,529 psi | 55% | 2379 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,701 psi | 52% | 1585 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 42,163 psi | 82% | 2641 fps | 98.7% |
| IMR 4350 | 40.4 gr | 90% | 43,236 psi | 84% | 2687 fps | 95% |
| IMR 4451 Enduron | <<locked>> | 84% | 42,076 psi | 82% | 2641 fps | 95.1% |
| IMR 4831 | <<locked>> | 84% | 34,055 psi | 66% | 2533 fps | 95.8% |
| Lovex S062 | <<locked>> | 80% | 42,264 psi | 82% | 2648 fps | 99.7% |
| Lovex S065 | <<locked>> | 82% | 36,753 psi | 71% | 2533 fps | 95.1% |
| Lovex S070 | <<locked>> | 88% | 42,206 psi | 82% | 2671 fps | 95.6% |
| Norma 203B | <<locked>> | 80% | 42,061 psi | 82% | 2680 fps | 99% |
| Norma MRP | <<locked>> | 98% | 43,598 psi | 85% | 2831 fps | 95.6% |
| Norma URP | <<locked>> | 82% | 33,011 psi | 64% | 2520 fps | 95.2% |
| Ramshot Big Game | <<locked>> | 80% | 41,887 psi | 81% | 2697 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 88% | 39,175 psi | 76% | 2671 fps | 95.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,977 psi | 52% | 1621 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 40,799 psi | 79% | 2621 fps | 95.6% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 36,724 psi | 71% | 2671 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 34,983 psi | 68% | 2595 fps | 95.7% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 37,260 psi | 72% | 2661 fps | 95.7% |
| Rottweil R 903 | <<locked>> | 80% | 37,246 psi | 72% | 2575 fps | 98.6% |
| Shooters World Long Rifle | <<locked>> | 82% | 36,753 psi | 71% | 2533 fps | 95.1% |
| Shooters World Precision | <<locked>> | 80% | 42,264 psi | 82% | 2648 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 88% | 42,206 psi | 82% | 2671 fps | 95.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 38,261 psi | 74% | 2628 fps | 98.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 39,668 psi | 77% | 2523 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 41,046 psi | 80% | 2582 fps | 95% |
| Somchem S355 | <<locked>> | 80% | 37,942 psi | 74% | 2582 fps | 98.6% |
| Somchem S365 | <<locked>> | 80% | 27,717 psi | 54% | 2415 fps | 96.6% |
| Vihtavuori N135 | <<locked>> | 80% | 43,700 psi | 85% | 2641 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 36,129 psi | 70% | 2516 fps | 99.2% |
| Vihtavuori N160 | <<locked>> | 82% | 34,447 psi | 67% | 2523 fps | 95.7% |
| Vihtavuori N540 | <<locked>> | 80% | 42,453 psi | 82% | 2635 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 33,939 psi | 66% | 2523 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 88% | 31,038 psi | 60% | 2520 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 32,097 psi | 62% | 2444 fps | 97.1% |
| Winchester 760 | <<locked>> | 88% | 42,989 psi | 83% | 2743 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 92% | 28,790 psi | 56% | 2516 fps | 95.6% |
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 51 powders for .257 Roberts loaded with the .257 | 115gr | Nosler Ballistic Silver Tip. Norma MRP delivers the highest muzzle velocity at 2,890 fps; across all powders the maximum-charge window runs from 1,772 fps to 2,890 fps. Accurate 3100 gives the best case fill at 100 %, and 51 of the 51 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 115.0 gr projectile in 0.257" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-23, 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. IMR 4350, Alliant Reloder-26, Alliant Reloder-16 rank at the top here: for .257 Roberts with the .257 | 115gr | Nosler Ballistic Silver Tip 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.