Load data for .257 Roberts + 100gr Sierra GameKing
Based on C.I.P., the max. allowed case length is 2.233 in / 56.72 mm, the max. cartridge length is 2.775 in / 70.49 mm, and the max. allowed pressure is 51,488 PSI / 3,550 bar.
Based on C.I.P., the max. allowed case length is 2.233 in / 56.72 mm, the max. cartridge length is 2.775 in / 70.49 mm, and the max. allowed pressure is 51,488 PSI / 3,550 bar.
Load Specifications
ImperialMetric
Bullet:.257 | 100gr | GameKing
Cartridge:.257 Roberts load data
Case Length (L3):2.233" | 56.7 mm
Cartridge Length (COL/L6):•••
Seated Depth:0.491" | 12.5 mm
Case Capacity:58 gow | 3.76 cm³
Primer Size:Large Rifle (LR)
Max. Pressure (C.I.P.):51,488 psi | 3,550 bar
Barrel Length:24.0" | 610 mm
Min. Twist Rate:1:11.5
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Community Loads for .257 Roberts + 100gr Sierra GameKing
Real loads for this combination shared by our community. Charge weights are only fully visible with an active Pro licence.
| Powder | Charge (gr) | C.O.L. | Barrel Length | Velocity (fps) | Pressure (psi) |
|---|---|---|---|---|---|
| 41.5 gr | 2.775" | 22.0" | 2762 fps | ••• | |
| 43.0 gr | 2.775" | 22.0" | 2851 fps | ••• | |
| 38.9 gr | 2.775" | 22.0" | 2793 fps | ••• | |
| ••• | 2.775" | 22.0" | 2883 fps | ••• | |
| ••• | 2.775" | 22.0" | 2876 fps | ••• | |
| ••• | 2.775" | 22.0" | 2529 fps | ••• | |
| ••• | 2.775" | 22.0" | 2608 fps | ••• | |
| ••• | 2.775" | 22.0" | 2690 fps | ••• | |
| ••• | 2.775" | 22.0" | 2771 fps | ••• | |
| ••• | 2.775" | 22.0" | 2767 fps | ••• | |
| ••• | 2.775" | 22.0" | 2871 fps | ••• | |
| ••• | 2.775" | 22.0" | 2614 fps | ••• | |
| ••• | 2.775" | 22.0" | 2712 fps | ••• | |
| ••• | 2.775" | 22.0" | 2811 fps | ••• | |
| ••• | 2.775" | 22.0" | 2908 fps | ••• | |
| ••• | 2.775" | 22.0" | 2833 fps | ••• | |
| ••• | 2.775" | 22.0" | 2902 fps | ••• | |
| ••• | 2.775" | 22.0" | 2748 fps | ••• | |
| ••• | 2.775" | 22.0" | 2844 fps | ••• | |
| ••• | 2.775" | 22.0" | 2849 fps | ••• | |
Charge weights beyond the first rows and all pressure values are only visible with an active Pro licence.