Load Specifications
Load data in caliber .257 Roberts with .257 | 117gr | Winchester Powerpoint bullet and 48 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, Norma MRP 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 3100 | <<locked>> | 98% | 44,599 psi | 87% | 2746 fps | 97.6% |
| Accurate 4350 | <<locked>> | 88% | 43,569 psi | 85% | 2746 fps | 98.8% |
| ADI AR 2208 | <<locked>> | 82% | 45,237 psi | 88% | 2703 fps | 99.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 45,382 psi | 88% | 2730 fps | 99.9% |
| Alliant Reloder-16 | <<locked>> | 90% | 45,295 psi | 88% | 2815 fps | 99.3% |
| Alliant Reloder-17 | <<locked>> | 86% | 45,484 psi | 88% | 2838 fps | 99.9% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 44,904 psi | 87% | 2825 fps | 99.9% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 39,508 psi | 77% | 2730 fps | 96.9% |
| Alliant Reloder-26 | <<locked>> | 96% | 44,280 psi | 86% | 2884 fps | 98.9% |
| Bofors RP3 | <<locked>> | 82% | 45,353 psi | 88% | 2736 fps | 99.9% |
| Bofors RP7 | <<locked>> | 86% | 45,556 psi | 88% | 2707 fps | 96.2% |
| Hodgdon H380 | <<locked>> | 82% | 45,847 psi | 89% | 2743 fps | 98.8% |
| Hodgdon H414 | <<locked>> | 88% | 45,992 psi | 89% | 2799 fps | 97% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 44,933 psi | 87% | 2746 fps | 99.8% |
| Hodgdon Superformance | <<locked>> | 88% | 45,658 psi | 89% | 2818 fps | 96.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,056 psi | 70% | 1785 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 46,296 psi | 90% | 2743 fps | 96.5% |
| IMR 4451 Enduron | <<locked>> | 84% | 44,527 psi | 86% | 2690 fps | 96.4% |
| IMR 4831 | <<locked>> | 90% | 44,570 psi | 87% | 2749 fps | 99% |
| Lovex S065 | <<locked>> | 86% | 44,295 psi | 86% | 2687 fps | 97.8% |
| Lovex S070 | <<locked>> | 88% | 45,078 psi | 88% | 2723 fps | 97% |
| Lovex S071ᴾ | <<locked>> | 100% | 39,697 psi | 77% | 2651 fps | 96.4% |
| Norma MRP | <<locked>> | 96% | 43,874 psi | 85% | 2835 fps | 96.3% |
| Norma URP | <<locked>> | 90% | 46,151 psi | 90% | 2795 fps | 99.1% |
| Ramshot Hunter | <<locked>> | 90% | 45,078 psi | 88% | 2789 fps | 97.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,622 psi | 71% | 1824 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 46,311 psi | 90% | 2726 fps | 97.6% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 45,150 psi | 88% | 2838 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 46,412 psi | 90% | 2825 fps | 99% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 45,701 psi | 89% | 2844 fps | 98.8% |
| Rottweil R 903 | <<locked>> | 84% | 45,556 psi | 88% | 2733 fps | 99.9% |
| Rottweil R 907 | <<locked>> | 86% | 45,556 psi | 88% | 2707 fps | 96.2% |
| Shooters World Long Rifle | <<locked>> | 86% | 44,295 psi | 86% | 2687 fps | 97.8% |
| Shooters World SW4350 | <<locked>> | 88% | 45,078 psi | 88% | 2723 fps | 97% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 43,932 psi | 85% | 2736 fps | 99.5% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 44,628 psi | 87% | 2602 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 46,557 psi | 90% | 2687 fps | 97.1% |
| Somchem S355 | <<locked>> | 84% | 46,079 psi | 89% | 2733 fps | 99.9% |
| Somchem S365 | <<locked>> | 92% | 44,686 psi | 87% | 2805 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 44,324 psi | 86% | 2736 fps | 95.9% |
| Vihtavuori N150 | <<locked>> | 84% | 43,976 psi | 85% | 2664 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 45,034 psi | 87% | 2740 fps | 98.9% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 46,267 psi | 90% | 2759 fps | 95.9% |
| Vihtavuori N550 | <<locked>> | 88% | 44,599 psi | 87% | 2746 fps | 98.7% |
| Vihtavuori N555 | <<locked>> | 96% | 44,121 psi | 86% | 2799 fps | 99.3% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 44,585 psi | 87% | 2713 fps | 99.9% |
| Winchester 760 | <<locked>> | 88% | 46,282 psi | 90% | 2802 fps | 97.1% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 40,466 psi | 79% | 2861 fps | 100% |
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>> | 92% | 36,172 psi | 70% | 2575 fps | 95.2% |
| Accurate 4350 | <<locked>> | 80% | 33,257 psi | 65% | 2523 fps | 96% |
| ADI AR 2208 | <<locked>> | 80% | 42,264 psi | 82% | 2648 fps | 98.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 42,409 psi | 82% | 2674 fps | 99.7% |
| Alliant Reloder-16 | 37 gr | 80% | 33,069 psi | 64% | 2533 fps | 96.1% |
| Alliant Reloder-17 | <<locked>> | 80% | 36,956 psi | 72% | 2657 fps | 98.9% |
| Alliant Reloder-23 | <<locked>> | 86% | 28,906 psi | 56% | 2441 fps | 95.9% |
| Alliant Reloder-25 | <<locked>> | 98% | 36,970 psi | 72% | 2667 fps | 95.9% |
| Alliant Reloder-26 | 44.9 gr | 88% | 33,301 psi | 65% | 2618 fps | 95.3% |
| Bofors RP3 | <<locked>> | 80% | 42,583 psi | 83% | 2684 fps | 99.8% |
| Bofors RP7 | <<locked>> | 84% | 42,902 psi | 83% | 2654 fps | 95.5% |
| Hodgdon H380 | <<locked>> | 80% | 43,149 psi | 84% | 2690 fps | 98.3% |
| Hodgdon H414 | <<locked>> | 84% | 40,350 psi | 78% | 2684 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 30,414 psi | 59% | 2428 fps | 96.8% |
| Hodgdon Superformance | <<locked>> | 86% | 42,409 psi | 82% | 2753 fps | 95.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,890 psi | 52% | 1594 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 43,308 psi | 84% | 2684 fps | 95.6% |
| IMR 4451 Enduron | <<locked>> | 82% | 41,684 psi | 81% | 2631 fps | 95.6% |
| IMR 4831 | <<locked>> | 80% | 32,082 psi | 62% | 2477 fps | 95.6% |
| Lovex S065 | <<locked>> | 80% | 36,724 psi | 71% | 2526 fps | 95.7% |
| Lovex S070 | <<locked>> | 84% | 39,682 psi | 77% | 2612 fps | 95.4% |
| Lovex S071 | <<locked>> | 98% | 37,231 psi | 72% | 2598 fps | 95.5% |
| Norma MRP | 46.5 gr | 94% | 41,002 psi | 80% | 2772 fps | 95.4% |
| Norma URP | <<locked>> | 80% | 33,199 psi | 64% | 2516 fps | 95.8% |
| Ramshot Hunter | <<locked>> | 84% | 36,825 psi | 72% | 2612 fps | 95.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,195 psi | 53% | 1627 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 43,308 psi | 84% | 2671 fps | 96.9% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 39,276 psi | 76% | 2720 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 32,880 psi | 64% | 2533 fps | 95.4% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 34,664 psi | 67% | 2592 fps | 95.3% |
| Rottweil R 903 | <<locked>> | 80% | 39,900 psi | 77% | 2625 fps | 99.4% |
| Rottweil R 907 | <<locked>> | 84% | 42,902 psi | 83% | 2654 fps | 95.5% |
| Shooters World Long Rifle | <<locked>> | 80% | 36,724 psi | 71% | 2526 fps | 95.7% |
| Shooters World SW4350 | <<locked>> | 84% | 39,682 psi | 77% | 2612 fps | 95.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 41,017 psi | 80% | 2677 fps | 99.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 41,901 psi | 81% | 2556 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 84% | 40,901 psi | 79% | 2575 fps | 95.6% |
| Somchem S355 | <<locked>> | 80% | 40,495 psi | 79% | 2628 fps | 99.3% |
| Somchem S365 | <<locked>> | 80% | 29,805 psi | 58% | 2470 fps | 98% |
| Somchem S385 | <<locked>> | 92% | 41,394 psi | 80% | 2680 fps | 95% |
| Vihtavuori N150 | <<locked>> | 80% | 38,551 psi | 75% | 2559 fps | 99.7% |
| Vihtavuori N160 | <<locked>> | 80% | 34,751 psi | 67% | 2523 fps | 96.3% |
| Vihtavuori N165 | <<locked>> | 98% | 43,482 psi | 84% | 2707 fps | 95.1% |
| Vihtavuori N550 | <<locked>> | 80% | 34,229 psi | 66% | 2520 fps | 95.9% |
| Vihtavuori N555 | <<locked>> | 84% | 29,559 psi | 57% | 2464 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 34,040 psi | 66% | 2493 fps | 98.3% |
| Winchester 760 | <<locked>> | 84% | 40,350 psi | 78% | 2684 fps | 95.4% |
| Winchester StaBALL HD | <<locked>> | 88% | 27,282 psi | 53% | 2464 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 48 powders for .257 Roberts loaded with the .257 | 117gr | Winchester Powerpoint. Alliant Reloder-26 delivers the highest muzzle velocity at 2,884 fps; across all powders the maximum-charge window runs from 1,785 fps to 2,884 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 70–90 %, leaving at least 10 % headroom. The 117.0 gr projectile in 0.257" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-23, Alliant Reloder-25, 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. Alliant Reloder-26, Norma MRP, Alliant Reloder-16 rank at the top here: for .257 Roberts with the .257 | 117gr | Winchester Powerpoint 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.