Load Specifications
Load data in caliber .38 Long Colt with .355 | 147gr | X-TREME RP HP bullet and 3 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 ≥ 60% and propellant combustion ≥ 80%. 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: 4"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Hodgdon TrailBoss | <<locked>> | 92% | 11,356 psi | 87% | 627 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 96% | 11,502 psi | 88% | 643 fps | 98.8% |
| Vihtavuori N32C Tin Star² | <<locked>> | 64% | 11,327 psi | 87% | 620 fps | 100% |
Start Load - Barrel Length: 4"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Hodgdon TrailBoss² | <<locked>> | 60% | 7,150 psi | 55% | 495 fps | 97.2% |
| ReloadSwiss RS 14*² | <<locked>> | 60% | 6,817 psi | 52% | 486 fps | 92.5% |
| Vihtavuori N32C Tin Star² | <<locked>> | 60% | 10,022 psi | 77% | 591 fps | 100% |
* not dangerous but load has suboptimal powder burnt with possible characteristics such as extensive muzzle flash or inaccurate loads.
² fill rate low - you might want to consider using a filler to ensure proper ignition.
This overview compares 3 powders for .38 Long Colt loaded with the .355 | 147gr | X-TREME RP HP. ReloadSwiss RS 14 delivers the highest muzzle velocity at 643 fps; across all powders the maximum-charge window runs from 620 fps to 643 fps. ReloadSwiss RS 14 gives the best case fill at 96 %, and 2 of the 3 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (90 MPa), the top charges use 87–88 %, leaving at least 12 % headroom. Hodgdon TrailBoss, ReloadSwiss RS 14, Vihtavuori N32C Tin Star 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.