Load Specifications
Load data in caliber 9 mm Steyr with .356 | 121gr | Hornady HAP bullet and 12 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% | 16,201 psi | 83% | 1030 fps | 95.3% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 76% | 17,405 psi | 89% | 1017 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 13,068 psi | 67% | 876 fps | 100% |
| Maxam CSB 1² | <<locked>> | 64% | 17,071 psi | 87% | 1014 fps | 99.6% |
| Maxam CSB 2² | <<locked>> | 64% | 17,405 psi | 89% | 1047 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 11,429 psi | 58% | 860 fps | 99.7% |
| ReloadSwiss RS 20² | <<locked>> | 64% | 15,954 psi | 81% | 1050 fps | 97.2% |
| SNPE Vectan A0² | <<locked>> | 64% | 17,347 psi | 89% | 1024 fps | 95.9% |
| Vihtavuori 3N37*² | <<locked>> | 64% | 15,563 psi | 79% | 1030 fps | 87.3% |
| Vihtavuori N32C Tin Star | <<locked>> | 84% | 17,202 psi | 88% | 951 fps | 100% |
| Vihtavuori N350*² | <<locked>> | 72% | 17,187 psi | 88% | 1073 fps | 89.7% |
| Winchester AutoComp ² | <<locked>> | 64% | 17,202 psi | 88% | 1033 fps | 99.2% |
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% | 11,473 psi | 59% | 889 fps | 89.7% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 11,371 psi | 58% | 873 fps | 99.9% |
| Hodgdon TrailBoss² | 2.4 gr | 60% | 5,932 psi | 30% | 630 fps | 96.8% |
| Maxam CSB 1² | <<locked>> | 60% | 15,142 psi | 77% | 968 fps | 98.9% |
| Maxam CSB 2² | <<locked>> | 60% | 15,374 psi | 79% | 1004 fps | 100% |
| ReloadSwiss RS 14*² | 2.5 gr | 60% | 5,729 psi | 29% | 627 fps | 91.9% |
| ReloadSwiss RS 20² | <<locked>> | 60% | 14,228 psi | 73% | 1001 fps | 95.7% |
| SNPE Vectan A0*² | <<locked>> | 60% | 14,982 psi | 77% | 965 fps | 93.9% |
| Vihtavuori 3N37*² | <<locked>> | 60% | 14,040 psi | 72% | 988 fps | 85.4% |
| Vihtavuori N32C Tin Star² | <<locked>> | 60% | 9,776 psi | 50% | 781 fps | 100% |
| Vihtavuori N350*² | <<locked>> | 68% | 15,490 psi | 79% | 1027 fps | 87.7% |
| Winchester AutoComp ² | <<locked>> | 60% | 15,490 psi | 79% | 991 fps | 98.4% |
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 12 powders for 9 mm Steyr loaded with the .356 | 121gr | Hornady HAP. Vihtavuori N350 delivers the highest muzzle velocity at 1,073 fps; across all powders the maximum-charge window runs from 860 fps to 1,073 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 3 of the 12 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (135 MPa), the top charges use 58–89 %, 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. Hodgdon TrailBoss, ReloadSwiss RS 14 rank at the top here: for 9 mm Steyr with the .356 | 121gr | Hornady HAP they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Vihtavuori 3N37, Vihtavuori N350 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.