Load Specifications
Load data in caliber .38-40 Win. with .400 | 135gr | Sierra JHP FN bullet and 2 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: 20"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Hodgdon TrailBoss | <<locked>> | 88% | 14,837 psi | 89% | 1421 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 92% | 14,808 psi | 89% | 1480 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 20"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Hodgdon TrailBoss | 8.1 gr | 80% | 12,792 psi | 77% | 1352 fps | 100% |
| ReloadSwiss RS 14 | 8.3 gr | 80% | 12,009 psi | 72% | 1375 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
This overview compares 2 powders for .38-40 Win. loaded with the .400 | 135gr | Sierra JHP FN. ReloadSwiss RS 14 delivers the highest muzzle velocity at 1,480 fps; across all powders the maximum-charge window runs from 1,421 fps to 1,480 fps. ReloadSwiss RS 14 gives the best case fill at 92 %, and 2 of the 2 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (115 MPa), the top charges use 89–89 %, leaving at least 11 % headroom. ReloadSwiss RS 14, Hodgdon TrailBoss rank at the top here: for .38-40 Win. with the .400 | 135gr | Sierra JHP FN 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.