Load Specifications
Load data in caliber .455 MK II with .452 | 185gr | H&N HP HS bullet and 9 powders. The key underlying parameters are shown in the table above.
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 1250*² | <<locked>> | 64% | 11,066 psi | 85% | 781 fps | 88.7% |
| Alliant BE-86*² | <<locked>> | 64% | 11,182 psi | 86% | 797 fps | 92.3% |
| Baschieri & Pellagri 102 Pistol | <<locked>> | 80% | 11,168 psi | 86% | 804 fps | 96.5% |
| Hodgdon TrailBoss*ᴾ | <<locked>> | 100% | 7,107 psi | 54% | 653 fps | 93.6% |
| Maxam CSB 1*² | <<locked>> | 64% | 10,573 psi | 81% | 764 fps | 88% |
| Maxam CSB 2*² | <<locked>> | 68% | 10,414 psi | 80% | 817 fps | 94.4% |
| Vihtavuori N32C Tin Star | <<locked>> | 88% | 10,950 psi | 84% | 778 fps | 100% |
| Vihtavuori N330*² | <<locked>> | 64% | 11,647 psi | 89% | 833 fps | 91.6% |
| Winchester AutoComp *² | <<locked>> | 68% | 11,748 psi | 90% | 810 fps | 88.3% |
Start Load - Barrel Length: 4"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate Solo 1250*² | <<locked>> | 60% | 9,732 psi | 75% | 741 fps | 86.2% |
| Alliant BE-86*² | <<locked>> | 60% | 9,587 psi | 73% | 748 fps | 89.6% |
| Baschieri & Pellagri 102 Pistol*² | <<locked>> | 60% | 6,150 psi | 47% | 627 fps | 85.8% |
| Hodgdon TrailBoss* | <<locked>> | 80% | 4,844 psi | 37% | 554 fps | 86.3% |
| Maxam CSB 1*² | <<locked>> | 60% | 9,340 psi | 72% | 725 fps | 85.6% |
| Maxam CSB 2*² | <<locked>> | 60% | 7,977 psi | 61% | 732 fps | 89.5% |
| Vihtavuori N32C Tin Star*² | <<locked>> | 60% | 5,149 psi | 39% | 581 fps | 93.4% |
| Vihtavuori N330*² | <<locked>> | 60% | 10,327 psi | 79% | 791 fps | 89.2% |
| Winchester AutoComp *² | <<locked>> | 64% | 10,588 psi | 81% | 774 fps | 86.3% |
* 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 2 powders for .455 MK II loaded with the .452 | 185gr | H&N HP HS. Vihtavuori N32C Tin Star delivers the highest muzzle velocity at 778 fps; across all powders the maximum-charge window runs from 653 fps to 778 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 2 of the 2 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (90 MPa), the top charges use 54–84 %, leaving at least 16 % headroom. Hodgdon TrailBoss 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. As outliers, Hodgdon TrailBoss burn incompletely and react more sensitively to barrel length and temperature. Hodgdon TrailBoss, 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.