Load Specifications
Load data in caliber .257 Roberts with .257 | 100gr | Sierra MatchKing bullet and 54 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-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 2495 | <<locked>> | 84% | 46,079 psi | 89% | 2881 fps | 100% |
| Accurate 4064 | <<locked>> | 86% | 46,209 psi | 90% | 2927 fps | 100% |
| Accurate 4350 | <<locked>> | 94% | 45,556 psi | 88% | 2979 fps | 97.7% |
| ADI AR 2208 | <<locked>> | 86% | 44,991 psi | 87% | 2890 fps | 98% |
| Alliant Power Pro 2000-MR | <<locked>> | 84% | 45,774 psi | 89% | 3038 fps | 98.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 44,933 psi | 87% | 2920 fps | 99.2% |
| Alliant Reloder-15 | <<locked>> | 84% | 45,266 psi | 88% | 2930 fps | 98.2% |
| Alliant Reloder-16 | <<locked>> | 94% | 44,498 psi | 86% | 2986 fps | 97.7% |
| Alliant Reloder-17 | <<locked>> | 90% | 44,657 psi | 87% | 3015 fps | 99.1% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 38,232 psi | 74% | 2864 fps | 97.5% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 42,975 psi | 83% | 3031 fps | 96.6% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 46,354 psi | 90% | 2949 fps | 98% |
| Bofors RP3 | <<locked>> | 86% | 44,657 psi | 87% | 2923 fps | 99.2% |
| Hodgdon H380 | <<locked>> | 86% | 45,803 psi | 89% | 2933 fps | 97.2% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 43,729 psi | 85% | 2920 fps | 98.8% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 46,180 psi | 90% | 2982 fps | 99.4% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,462 psi | 69% | 1909 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 45,353 psi | 88% | 2904 fps | 99% |
| IMR 4064 | <<locked>> | 84% | 44,469 psi | 86% | 2871 fps | 98.1% |
| IMR 4831 | <<locked>> | 96% | 46,383 psi | 90% | 2979 fps | 98% |
| IMR 4895 | <<locked>> | 84% | 46,412 psi | 90% | 2966 fps | 98.9% |
| Lovex D073.6 | <<locked>> | 82% | 46,093 psi | 90% | 2927 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 44,367 psi | 86% | 2877 fps | 99.3% |
| Lovex S065 | <<locked>> | 90% | 44,019 psi | 85% | 2864 fps | 95.8% |
| Norma 201 | <<locked>> | 82% | 45,876 psi | 89% | 2897 fps | 99.5% |
| Norma 202 | <<locked>> | 82% | 46,195 psi | 90% | 2904 fps | 100% |
| Norma 203B | <<locked>> | 84% | 44,585 psi | 87% | 2917 fps | 98.5% |
| Norma URP | <<locked>> | 94% | 45,208 psi | 88% | 2972 fps | 97.5% |
| Ramshot Big Game | <<locked>> | 84% | 44,251 psi | 86% | 2933 fps | 98.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,882 psi | 70% | 1955 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 44,759 psi | 87% | 2986 fps | 98.1% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 44,730 psi | 87% | 3031 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 94% | 45,237 psi | 88% | 2999 fps | 97.4% |
| ReloadSwiss RS 70 | <<locked>> | 94% | 45,150 psi | 88% | 3012 fps | 96.7% |
| Rottweil R 902 | <<locked>> | 84% | 46,514 psi | 90% | 2897 fps | 99.5% |
| Rottweil R 903 | <<locked>> | 88% | 44,817 psi | 87% | 2920 fps | 99.1% |
| Shooters World Long Rifle | <<locked>> | 90% | 44,019 psi | 85% | 2864 fps | 95.8% |
| Shooters World Match Rifle | <<locked>> | 82% | 46,093 psi | 90% | 2927 fps | 100% |
| Shooters World Precision | <<locked>> | 84% | 44,367 psi | 86% | 2877 fps | 99.3% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 46,282 psi | 90% | 2979 fps | 98.8% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 45,397 psi | 88% | 2910 fps | 98.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 44,498 psi | 86% | 2799 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 45,629 psi | 89% | 2923 fps | 99% |
| Somchem S365 | <<locked>> | 98% | 46,151 psi | 90% | 3038 fps | 99.9% |
| Vihtavuori N135 | <<locked>> | 84% | 45,788 psi | 89% | 2874 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 43,685 psi | 85% | 2831 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 46,427 psi | 90% | 2904 fps | 99.8% |
| Vihtavuori N160 | <<locked>> | 92% | 44,237 psi | 86% | 2913 fps | 97.2% |
| Vihtavuori N540 | <<locked>> | 84% | 45,005 psi | 87% | 2874 fps | 100% |
| Vihtavuori N550 | <<locked>> | 94% | 46,557 psi | 90% | 2976 fps | 97.6% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 41,655 psi | 81% | 2946 fps | 97.5% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 44,570 psi | 87% | 2894 fps | 99.1% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 34,403 psi | 67% | 2844 fps | 96.8% |
| Winchester StaBALL Match | <<locked>> | 82% | 44,817 psi | 87% | 2913 fps | 99% |
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 2495 | <<locked>> | 80% | 40,466 psi | 79% | 2779 fps | 100% |
| Accurate 4064 | <<locked>> | 80% | 38,247 psi | 74% | 2766 fps | 99.8% |
| Accurate 4350 | <<locked>> | 88% | 36,680 psi | 71% | 2789 fps | 95.1% |
| ADI AR 2208 | <<locked>> | 80% | 37,362 psi | 73% | 2723 fps | 96% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 39,813 psi | 77% | 2900 fps | 96.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 36,956 psi | 72% | 2746 fps | 97.6% |
| Alliant Reloder-15 | <<locked>> | 80% | 39,697 psi | 77% | 2812 fps | 96.9% |
| Alliant Reloder-16 | 40.1 gr | 88% | 37,014 psi | 72% | 2805 fps | 95.2% |
| Alliant Reloder-17 | 40.2 gr | 82% | 34,113 psi | 66% | 2756 fps | 96% |
| Alliant Reloder-23 | <<locked>> | 96% | 33,852 psi | 66% | 2746 fps | 95.8% |
| Alliant Reloder-26 | <<locked>> | 98% | 40,016 psi | 78% | 2959 fps | 95.5% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 43,352 psi | 84% | 2890 fps | 97.3% |
| Bofors RP3 | <<locked>> | 80% | 36,564 psi | 71% | 2746 fps | 97.6% |
| Hodgdon H380 | <<locked>> | 82% | 40,132 psi | 78% | 2808 fps | 95.6% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 31,792 psi | 62% | 2635 fps | 95.1% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 40,422 psi | 79% | 2864 fps | 98.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,266 psi | 51% | 1706 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 42,627 psi | 83% | 2848 fps | 98.5% |
| IMR 4064 | <<locked>> | 80% | 39,218 psi | 76% | 2759 fps | 96.8% |
| IMR 4831 | <<locked>> | 90% | 38,000 psi | 74% | 2802 fps | 95.7% |
| IMR 4895 | <<locked>> | 80% | 40,640 psi | 79% | 2848 fps | 97.7% |
| Lovex D073.6 | <<locked>> | 80% | 42,975 psi | 83% | 2864 fps | 99.9% |
| Lovex S062 | <<locked>> | 80% | 39,160 psi | 76% | 2766 fps | 98.5% |
| Lovex S065 | <<locked>> | 88% | 41,408 psi | 80% | 2808 fps | 95% |
| Norma 201 | <<locked>> | 80% | 43,105 psi | 84% | 2838 fps | 99.1% |
| Norma 202 | <<locked>> | 80% | 43,381 psi | 84% | 2851 fps | 100% |
| Norma 203B | <<locked>> | 80% | 39,059 psi | 76% | 2802 fps | 97.3% |
| Norma URP | <<locked>> | 88% | 37,043 psi | 72% | 2792 fps | 95.1% |
| Ramshot Big Game | <<locked>> | 80% | 38,508 psi | 75% | 2805 fps | 96.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,455 psi | 51% | 1742 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 41,539 psi | 81% | 2917 fps | 97.3% |
| ReloadSwiss RS 60 | 39.2 gr | 80% | 33,910 psi | 66% | 2766 fps | 98.4% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 39,276 psi | 76% | 2871 fps | 95.6% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 42,148 psi | 82% | 2943 fps | 95.7% |
| Rottweil R 902 | <<locked>> | 80% | 41,104 psi | 80% | 2789 fps | 98.8% |
| Rottweil R 903 | <<locked>> | 80% | 34,389 psi | 67% | 2687 fps | 96.6% |
| Shooters World Long Rifle | <<locked>> | 88% | 41,408 psi | 80% | 2808 fps | 95% |
| Shooters World Match Rifle | <<locked>> | 80% | 42,975 psi | 83% | 2864 fps | 99.9% |
| Shooters World Precision | <<locked>> | 80% | 39,160 psi | 76% | 2766 fps | 98.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 35,317 psi | 69% | 2736 fps | 95.9% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 42,438 psi | 82% | 2851 fps | 98.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 36,985 psi | 72% | 2651 fps | 99.9% |
| Somchem S355 | <<locked>> | 80% | 35,288 psi | 69% | 2694 fps | 96.6% |
| Somchem S365 | <<locked>> | 84% | 29,182 psi | 57% | 2618 fps | 95.5% |
| Vihtavuori N135 | <<locked>> | 80% | 40,422 psi | 79% | 2776 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 41,031 psi | 80% | 2779 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 33,504 psi | 65% | 2628 fps | 97.5% |
| Vihtavuori N160 | <<locked>> | 88% | 38,667 psi | 75% | 2795 fps | 95.6% |
| Vihtavuori N540 | <<locked>> | 80% | 39,523 psi | 77% | 2762 fps | 99.7% |
| Vihtavuori N550 | <<locked>> | 88% | 38,087 psi | 74% | 2795 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 96% | 36,535 psi | 71% | 2831 fps | 95.9% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 31,981 psi | 62% | 2598 fps | 95.4% |
| Winchester StaBALL HD | <<locked>> | 98% | 32,155 psi | 62% | 2769 fps | 95.4% |
| Winchester StaBALL Match | <<locked>> | 80% | 41,858 psi | 81% | 2854 fps | 98.5% |
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 | 100gr | Sierra MatchKing. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,038 fps; across all powders the maximum-charge window runs from 1,909 fps to 3,038 fps. Accurate 3100 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 100.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-23, Alliant Reloder-26 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-16 rank at the top here: for .257 Roberts with the .257 | 100gr | Sierra MatchKing they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 2700, Accurate 3100, ADI AR 2209 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.