Load Specifications
Load data in caliber 8 x 57 R 360 with .321 | 170gr | H&N KS F bullet and 10 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N135, IMR 3031 and Accurate 2495.
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 ≥ 80% and propellant combustion ≥ 95%. 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: 23.62"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 84% | 31,270 psi | 88% | 2211 fps | 98.1% |
| Accurate 2495 | <<locked>> | 94% | 32,068 psi | 90% | 2303 fps | 98.8% |
| Alliant AR-Comp | <<locked>> | 86% | 30,937 psi | 87% | 2277 fps | 99.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 32,126 psi | 90% | 1512 fps | 100% |
| IMR 3031 | <<locked>> | 88% | 31,285 psi | 88% | 2293 fps | 97.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 31,662 psi | 89% | 1545 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 31,531 psi | 89% | 2185 fps | 96.5% |
| Somchem S335 | <<locked>> | 86% | 31,662 psi | 89% | 2195 fps | 96.4% |
| Vihtavuori N133 | <<locked>> | 84% | 30,385 psi | 86% | 2162 fps | 97.7% |
| Vihtavuori N135 | <<locked>> | 90% | 30,342 psi | 85% | 2241 fps | 98.1% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 23.62"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 27,325 psi | 77% | 2119 fps | 96.8% |
| Accurate 2495 | 34.9 gr | 86% | 24,120 psi | 68% | 2113 fps | 96% |
| Alliant AR-Comp | <<locked>> | 80% | 25,309 psi | 71% | 2133 fps | 98.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 23,467 psi | 66% | 1348 fps | 100% |
| IMR 3031 | 33.6 gr | 84% | 27,456 psi | 77% | 2195 fps | 95.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 23,206 psi | 65% | 1381 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 29,834 psi | 84% | 2146 fps | 95.8% |
| Somchem S335 | <<locked>> | 84% | 29,457 psi | 83% | 2142 fps | 95.5% |
| Vihtavuori N133 | <<locked>> | 80% | 26,643 psi | 75% | 2070 fps | 96.2% |
| Vihtavuori N135 | 32.9 gr | 84% | 24,787 psi | 70% | 2100 fps | 95.8% |
Recommended = one of the top powders for this cartridge and bullet combination.
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 10 powders for 8 x 57 R 360 loaded with the .321 | 170gr | H&N KS F. Accurate 2495 delivers the highest muzzle velocity at 2,303 fps; across all powders the maximum-charge window runs from 1,512 fps to 2,303 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 10 of the 10 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (245 MPa), the top charges use 85–90 %, 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 N135, IMR 3031, Accurate 2495 rank at the top here: for 8 x 57 R 360 with the .321 | 170gr | H&N KS F they combine a high case fill with complete burn and sit in the upper velocity band. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.