Load Specifications
Load data in caliber .458 SOCOM with .458 | 400gr | Speer Soft Point Flat Nose bullet and 5 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 14 and Hodgdon TrailBoss.
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: 16"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 88% | 31,444 psi | 90% | 1654 fps | 97.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 28,979 psi | 83% | 1076 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 28,413 psi | 81% | 1102 fps | 100% |
| SNPE Vectan BA6 1/2 | <<locked>> | 82% | 31,198 psi | 89% | 1509 fps | 100% |
| Vihtavuori N120 | <<locked>> | 86% | 29,907 psi | 85% | 1608 fps | 98.1% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 16"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 82% | 26,223 psi | 75% | 1555 fps | 95.5% |
| Hodgdon TrailBoss | 12.3 gr | 80% | 21,132 psi | 60% | 958 fps | 100% |
| ReloadSwiss RS 14 | 12.6 gr | 80% | 20,871 psi | 60% | 984 fps | 100% |
| SNPE Vectan BA6 1/2 | <<locked>> | 80% | 29,689 psi | 85% | 1486 fps | 100% |
| Vihtavuori N120 | <<locked>> | 80% | 25,048 psi | 72% | 1509 fps | 96.2% |
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 12 powders for .458 SOCOM loaded with the .458 | 400gr | Speer Soft Point Flat Nose. ADI AR 2207 delivers the highest muzzle velocity at 1,654 fps; across all powders the maximum-charge window runs from 1,076 fps to 1,654 fps. Alliant AR-Comp gives the best case fill at 100 %, and 12 of the 12 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (241 MPa), the top charges use 81–90 %, leaving at least 10 % headroom. Alliant AR-Comp, Hodgdon TrailBoss, ReloadSwiss RS 14 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 14, Hodgdon TrailBoss rank at the top here: for .458 SOCOM with the .458 | 400gr | Speer Soft Point Flat Nose they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 1680, Alliant AR-Comp, Alliant Reloder-10x burn incompletely and react more sensitively to barrel length and temperature. Hodgdon TrailBoss, ReloadSwiss RS 14 stay subsonic at start load. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.