Load Specifications
Load data in caliber .38 S&W (Colt N.P.) with .358 | 148gr | Rim Rock SWC bullet and 14 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N32C Tin Star 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 |
|---|---|---|---|---|---|---|
| Accurate Solo 1250² | <<locked>> | 64% | 14,721 psi | 85% | 758 fps | 96.8% |
| Alliant BE-86² | <<locked>> | 64% | 15,200 psi | 87% | 771 fps | 99% |
| Alliant Herco* | <<locked>> | 80% | 15,490 psi | 89% | 797 fps | 91.7% |
| Alliant UNIQUE*² | <<locked>> | 64% | 14,199 psi | 82% | 768 fps | 90.1% |
| Baschieri & Pellagri 102 Pistol | <<locked>> | 80% | 15,505 psi | 89% | 778 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 10,240 psi | 59% | 633 fps | 99.7% |
| Maxam CSB 1² | <<locked>> | 64% | 14,156 psi | 81% | 741 fps | 96.4% |
| Maxam CSB 2² | <<locked>> | 68% | 14,808 psi | 85% | 791 fps | 99.9% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 9,427 psi | 54% | 630 fps | 96.7% |
| ReloadSwiss RS 20*² | <<locked>> | 68% | 14,446 psi | 83% | 791 fps | 92.9% |
| SNPE Vectan A0*² | <<locked>> | 68% | 15,679 psi | 90% | 768 fps | 91.4% |
| Vihtavuori N32C Tin Star | <<locked>> | 88% | 14,750 psi | 85% | 722 fps | 100% |
| Vihtavuori N340*² | <<locked>> | 64% | 14,837 psi | 85% | 771 fps | 91.3% |
| Winchester AutoComp ² | <<locked>> | 64% | 13,938 psi | 80% | 748 fps | 95% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 4"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate Solo 1250² | <<locked>> | 60% | 12,981 psi | 75% | 719 fps | 95.2% |
| Alliant BE-86² | <<locked>> | 60% | 12,865 psi | 74% | 722 fps | 97.5% |
| Alliant Herco*² | <<locked>> | 68% | 11,487 psi | 66% | 699 fps | 86.2% |
| Alliant UNIQUE*² | <<locked>> | 60% | 12,676 psi | 73% | 732 fps | 88% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 9,181 psi | 53% | 633 fps | 97% |
| Hodgdon TrailBoss*² | 1.6 gr | 60% | 5,149 psi | 30% | 463 fps | 92% |
| Maxam CSB 1*² | <<locked>> | 60% | 12,502 psi | 72% | 702 fps | 94.8% |
| Maxam CSB 2² | <<locked>> | 60% | 12,241 psi | 70% | 735 fps | 98.9% |
| ReloadSwiss RS 14*² | <<locked>> | 64% | 5,076 psi | 29% | 466 fps | 86.3% |
| ReloadSwiss RS 20*² | <<locked>> | 60% | 11,603 psi | 67% | 719 fps | 88.7% |
| SNPE Vectan A0*² | <<locked>> | 60% | 12,604 psi | 72% | 699 fps | 87.5% |
| Vihtavuori N32C Tin Star² | 2.1 gr | 60% | 7,585 psi | 44% | 564 fps | 99.9% |
| Vihtavuori N340*² | <<locked>> | 60% | 13,213 psi | 76% | 732 fps | 89.2% |
| Winchester AutoComp *² | <<locked>> | 60% | 12,589 psi | 72% | 715 fps | 93.5% |
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 3 powders for .38 S&W (Colt N.P.) loaded with the .358 | 148gr | Rim Rock SWC. Vihtavuori N32C Tin Star delivers the highest muzzle velocity at 722 fps; across all powders the maximum-charge window runs from 630 fps to 722 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 3 of the 3 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (120 MPa), the top charges use 54–85 %, leaving at least 15 % 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. Vihtavuori N32C Tin Star, Hodgdon TrailBoss rank at the top here: for .38 S&W (Colt N.P.) with the .358 | 148gr | Rim Rock SWC they combine a high case fill with complete burn and sit in the upper velocity band. 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.