Load Specifications
Load data in caliber .38 Special with .357 | 158gr | X-TREME SWC bullet and 7 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 ≥ 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 |
|---|---|---|---|---|---|---|
| ADI AP 100*² | <<locked>> | 68% | 18,826 psi | 87% | 909 fps | 87% |
| Alliant Herco² | <<locked>> | 64% | 19,160 psi | 88% | 896 fps | 99.2% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 64% | 18,405 psi | 85% | 830 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 18,782 psi | 86% | 801 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 17,738 psi | 82% | 807 fps | 100% |
| Rottweil P 806*² | <<locked>> | 64% | 19,290 psi | 89% | 971 fps | 92.2% |
| Vihtavuori N32C Tin Star² | <<locked>> | 72% | 19,667 psi | 90% | 797 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 4"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AP 100*² | <<locked>> | 64% | 17,289 psi | 79% | 876 fps | 85.5% |
| Alliant Herco² | <<locked>> | 60% | 17,535 psi | 81% | 863 fps | 98.5% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 16,737 psi | 77% | 804 fps | 100% |
| Hodgdon TrailBoss² | 2.8 gr | 60% | 9,427 psi | 43% | 600 fps | 100% |
| ReloadSwiss RS 14² | 2.9 gr | 60% | 9,224 psi | 42% | 607 fps | 99.8% |
| Rottweil P 806*² | <<locked>> | 60% | 17,216 psi | 79% | 925 fps | 90.2% |
| Vihtavuori N32C Tin Star² | <<locked>> | 60% | 14,910 psi | 69% | 719 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
* 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.
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 2 powders for .38 Special loaded with the .357 | 158gr | X-TREME SWC. ReloadSwiss RS 14 delivers the highest muzzle velocity at 807 fps; across all powders the maximum-charge window runs from 801 fps to 807 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 2 of the 2 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (150 MPa), the top charges use 82–86 %, leaving at least 14 % 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. ReloadSwiss RS 14, Hodgdon TrailBoss rank at the top here: for .38 Special with the .357 | 158gr | X-TREME SWC they combine a high case fill with complete burn and sit in the upper velocity band. 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.