Load Specifications
Load data in caliber 9 mm Steyr with .355 | 124gr | Geco HEXAGON bullet and 15 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, 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 |
|---|---|---|---|---|---|---|
| Accurate Solo 1250² | <<locked>> | 64% | 16,549 psi | 85% | 968 fps | 99.2% |
| Alliant BE-86² | <<locked>> | 64% | 16,766 psi | 86% | 974 fps | 100% |
| Alliant Herco | <<locked>> | 80% | 17,579 psi | 90% | 1027 fps | 95.7% |
| Alliant UNIQUE*² | <<locked>> | 64% | 16,288 psi | 83% | 994 fps | 94.6% |
| Baschieri & Pellagri 102 Pistol | <<locked>> | 80% | 17,463 psi | 89% | 981 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 11,734 psi | 60% | 814 fps | 100% |
| Maxam CSB 1² | <<locked>> | 68% | 17,376 psi | 89% | 981 fps | 99.5% |
| Maxam CSB 2² | <<locked>> | 68% | 17,492 psi | 89% | 1017 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 10,704 psi | 55% | 807 fps | 99.2% |
| ReloadSwiss RS 20² | <<locked>> | 68% | 15,824 psi | 81% | 1007 fps | 96.5% |
| SNPE Vectan A0² | <<locked>> | 68% | 17,303 psi | 88% | 981 fps | 95.1% |
| Somchem MS200² | <<locked>> | 64% | 17,172 psi | 88% | 991 fps | 96.2% |
| Vihtavuori N32C Tin Star | <<locked>> | 88% | 17,361 psi | 89% | 922 fps | 100% |
| Vihtavuori N340² | <<locked>> | 64% | 16,563 psi | 85% | 988 fps | 95.2% |
| Winchester AutoComp ² | <<locked>> | 64% | 15,983 psi | 82% | 965 fps | 98.2% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 5"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate Solo 1250² | <<locked>> | 60% | 14,373 psi | 73% | 915 fps | 98% |
| Alliant BE-86² | <<locked>> | 60% | 14,750 psi | 75% | 932 fps | 99.6% |
| Alliant Herco*² | <<locked>> | 60% | 10,573 psi | 54% | 827 fps | 87.3% |
| Alliant UNIQUE*² | <<locked>> | 60% | 14,286 psi | 73% | 945 fps | 92.6% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 10,269 psi | 52% | 807 fps | 99.2% |
| Hodgdon TrailBoss² | 2.1 gr | 60% | 5,584 psi | 29% | 587 fps | 95.3% |
| Maxam CSB 1² | <<locked>> | 60% | 13,822 psi | 71% | 899 fps | 97.7% |
| Maxam CSB 2² | <<locked>> | 60% | 13,779 psi | 70% | 935 fps | 100% |
| ReloadSwiss RS 14*² | 2.1 gr | 60% | 5,149 psi | 26% | 571 fps | 89.1% |
| ReloadSwiss RS 20*² | <<locked>> | 60% | 12,778 psi | 65% | 922 fps | 93.3% |
| SNPE Vectan A0*² | <<locked>> | 60% | 13,996 psi | 71% | 899 fps | 91.9% |
| Somchem MS200² | <<locked>> | 60% | 15,737 psi | 80% | 955 fps | 95.1% |
| Vihtavuori N32C Tin Star² | 2.8 gr | 60% | 8,630 psi | 44% | 722 fps | 100% |
| Vihtavuori N340*² | <<locked>> | 60% | 14,533 psi | 74% | 935 fps | 93.3% |
| Winchester AutoComp ² | <<locked>> | 60% | 14,185 psi | 72% | 922 fps | 97% |
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 15 powders for 9 mm Steyr loaded with the .355 | 124gr | Geco HEXAGON. Alliant Herco delivers the highest muzzle velocity at 1,027 fps; across all powders the maximum-charge window runs from 807 fps to 1,027 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 5 of the 15 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (135 MPa), the top charges use 55–90 %, 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. Vihtavuori N32C Tin Star, Hodgdon TrailBoss, ReloadSwiss RS 14 rank at the top here: for 9 mm Steyr with the .355 | 124gr | Geco HEXAGON they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Alliant UNIQUE burn incompletely and react more sensitively to barrel length and temperature. Accurate Solo 1250, Alliant BE-86, Alliant Herco 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.