Load Specifications
Load data in caliber .38 S&W (Colt N.P.) with .357 | 148gr | LOS WC bullet and 8 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 Herco*² | <<locked>> | 72% | 14,968 psi | 86% | 761 fps | 90.9% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 76% | 15,273 psi | 88% | 751 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 12,415 psi | 71% | 656 fps | 100% |
| Maxam CSB 1² | <<locked>> | 64% | 15,273 psi | 88% | 745 fps | 97.1% |
| Maxam CSB 2² | <<locked>> | 64% | 15,606 psi | 90% | 781 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 11,821 psi | 68% | 659 fps | 98.8% |
| ReloadSwiss RS 20*² | <<locked>> | 68% | 15,635 psi | 90% | 797 fps | 94% |
| Vihtavuori N32C Tin Star | <<locked>> | 80% | 14,663 psi | 84% | 696 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 Herco*² | <<locked>> | 60% | 11,400 psi | 66% | 669 fps | 85.8% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 10,573 psi | 61% | 646 fps | 98.4% |
| Hodgdon TrailBoss² | 1.6 gr | 60% | 7,020 psi | 40% | 495 fps | 96.7% |
| Maxam CSB 1² | <<locked>> | 60% | 13,677 psi | 79% | 709 fps | 95.8% |
| Maxam CSB 2² | <<locked>> | 60% | 13,953 psi | 80% | 748 fps | 99.6% |
| ReloadSwiss RS 14*² | 1.6 gr | 60% | 6,715 psi | 39% | 486 fps | 91.8% |
| ReloadSwiss RS 20*² | <<locked>> | 60% | 12,807 psi | 74% | 728 fps | 90.4% |
| Vihtavuori N32C Tin Star² | <<locked>> | 60% | 9,790 psi | 56% | 591 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 S&W (Colt N.P.) loaded with the .357 | 148gr | LOS WC. ReloadSwiss RS 14 delivers the highest muzzle velocity at 659 fps; across all powders the maximum-charge window runs from 656 fps to 659 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 (120 MPa), the top charges use 68–71 %, leaving at least 29 % 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 S&W (Colt N.P.) with the .357 | 148gr | LOS WC 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.