Load Specifications
Load data in caliber .45-70 Govt. with .458 | 325gr | Hornady FTX bullet and 4 powders. The key underlying parameters are shown in the table above.
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 |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 86% | 27,673 psi | 87% | 1926 fps | 96.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 28,398 psi | 89% | 1296 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 27,659 psi | 87% | 1322 fps | 100% |
| Vihtavuori N120 | <<locked>> | 86% | 28,123 psi | 88% | 1906 fps | 98.2% |
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 82% | 24,598 psi | 77% | 1850 fps | 95.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 20,566 psi | 64% | 1155 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 20,189 psi | 63% | 1181 fps | 100% |
| Vihtavuori N120 | <<locked>> | 80% | 23,554 psi | 74% | 1798 fps | 96.3% |
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 4 powders for .45-70 Govt. loaded with the .458 | 325gr | Hornady FTX. ADI AR 2207 delivers the highest muzzle velocity at 1,926 fps; across all powders the maximum-charge window runs from 1,296 fps to 1,926 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 4 of the 4 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (220 MPa), the top charges use 87–89 %, leaving at least 11 % headroom. 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. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.