Load Specifications
Load data in caliber 9 mm Steyr with .357 | 158gr | LOS SWC bullet and 11 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon TrailBoss and ReloadSwiss RS 14.
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: 5"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Alliant Herco² | <<locked>> | 72% | 17,593 psi | 90% | 850 fps | 97.6% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 72% | 16,679 psi | 85% | 794 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 14,634 psi | 75% | 712 fps | 100% |
| Maxam CSB 1² | <<locked>> | 64% | 17,695 psi | 90% | 814 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 13,300 psi | 68% | 709 fps | 100% |
| ReloadSwiss RS 20² | <<locked>> | 64% | 17,027 psi | 87% | 860 fps | 98.9% |
| Rottweil P 806*² | <<locked>> | 76% | 16,839 psi | 86% | 938 fps | 89.5% |
| SNPE Vectan BA7 1/2*² | <<locked>> | 68% | 17,100 psi | 87% | 833 fps | 89.5% |
| Vihtavuori 3N37*² | <<locked>> | 64% | 16,882 psi | 86% | 853 fps | 90.8% |
| Vihtavuori N32C Tin Star | <<locked>> | 80% | 17,303 psi | 88% | 748 fps | 100% |
| Vihtavuori N350*² | <<locked>> | 68% | 16,563 psi | 85% | 846 fps | 90.9% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 5"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Alliant Herco*² | <<locked>> | 60% | 13,053 psi | 67% | 745 fps | 93.8% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 12,546 psi | 64% | 712 fps | 100% |
| Hodgdon TrailBoss² | 1.8 gr | 60% | 7,745 psi | 40% | 535 fps | 99.8% |
| Maxam CSB 1² | <<locked>> | 60% | 16,027 psi | 82% | 781 fps | 99.8% |
| ReloadSwiss RS 14² | 1.8 gr | 60% | 7,353 psi | 38% | 528 fps | 97.3% |
| ReloadSwiss RS 20² | <<locked>> | 60% | 14,808 psi | 76% | 810 fps | 97.7% |
| Rottweil P 806*² | <<locked>> | 72% | 14,736 psi | 75% | 889 fps | 86.9% |
| SNPE Vectan BA7 1/2*² | <<locked>> | 60% | 13,967 psi | 71% | 761 fps | 85.8% |
| Vihtavuori 3N37*² | <<locked>> | 60% | 14,939 psi | 76% | 810 fps | 88.7% |
| Vihtavuori N32C Tin Star² | <<locked>> | 60% | 11,385 psi | 58% | 636 fps | 100% |
| Vihtavuori N350*² | <<locked>> | 60% | 13,314 psi | 68% | 771 fps | 87% |
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 11 powders for 9 mm Steyr loaded with the .357 | 158gr | LOS SWC. Rottweil P 806 delivers the highest muzzle velocity at 938 fps; across all powders the maximum-charge window runs from 709 fps to 938 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 3 of the 11 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (135 MPa), the top charges use 68–90 %, leaving at least 10 % 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. Hodgdon TrailBoss, ReloadSwiss RS 14 rank at the top here: for 9 mm Steyr with the .357 | 158gr | LOS SWC they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Rottweil P 806, SNPE Vectan BA7 1/2, Vihtavuori 3N37 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.