Load Specifications
Load data in caliber .38 Special with .357 | 158gr | Speer TMJ bullet and 6 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 |
|---|---|---|---|---|---|---|
| Alliant Herco² | <<locked>> | 64% | 17,956 psi | 83% | 892 fps | 98.8% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 64% | 17,999 psi | 83% | 846 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 17,941 psi | 82% | 807 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 16,578 psi | 76% | 810 fps | 100% |
| Rottweil P 806*² | <<locked>> | 64% | 17,956 psi | 83% | 958 fps | 90.9% |
| Vihtavuori N32C Tin Star² | <<locked>> | 68% | 19,377 psi | 89% | 814 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 |
|---|---|---|---|---|---|---|
| Alliant Herco² | <<locked>> | 60% | 16,462 psi | 76% | 860 fps | 98% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 15,853 psi | 73% | 807 fps | 100% |
| Hodgdon TrailBoss² | 3 gr | 60% | 8,050 psi | 37% | 591 fps | 100% |
| ReloadSwiss RS 14² | 3.1 gr | 60% | 7,716 psi | 35% | 591 fps | 98.6% |
| Rottweil P 806*² | <<locked>> | 60% | 15,519 psi | 71% | 902 fps | 88.1% |
| Vihtavuori N32C Tin Star² | <<locked>> | 60% | 15,795 psi | 73% | 758 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 6 powders for .38 Special loaded with the .357 | 158gr | Speer TMJ. Rottweil P 806 delivers the highest muzzle velocity at 958 fps; across all powders the maximum-charge window runs from 807 fps to 958 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 2 of the 6 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (150 MPa), the top charges use 76–89 %, 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. ReloadSwiss RS 14, Hodgdon TrailBoss rank at the top here: for .38 Special with the .357 | 158gr | Speer TMJ they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Rottweil P 806 burn incompletely and react more sensitively to barrel length and temperature. Alliant Herco, Baschieri & Pellagri 102 Pistol, Hodgdon TrailBoss 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.