Load Specifications
Load data in caliber .505 Mag. Gibbs with .505 | 410gr | Impala LW CFN bullet and 5 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 14 and Hodgdon TrailBoss.
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: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 4064 | <<locked>> | 82% | 34,592 psi | 88% | 2461 fps | 98.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,780 psi | 89% | 1686 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,157 psi | 90% | 1729 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 86% | 34,679 psi | 89% | 2530 fps | 96.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 33,620 psi | 86% | 2352 fps | 98.4% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 4064 | <<locked>> | 80% | 32,648 psi | 83% | 2411 fps | 97.6% |
| Hodgdon TrailBoss | 36.3 gr | 80% | 25,976 psi | 66% | 1506 fps | 100% |
| ReloadSwiss RS 14 | 37 gr | 80% | 26,237 psi | 67% | 1542 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 32,750 psi | 84% | 2477 fps | 95.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 31,734 psi | 81% | 2306 fps | 97.9% |
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 20 powders for .505 Mag. Gibbs loaded with the .505 | 410gr | Impala LW CFN. Somchem S365 delivers the highest muzzle velocity at 2,539 fps; across all powders the maximum-charge window runs from 1,686 fps to 2,539 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 20 of the 20 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (270 MPa), the top charges use 85–90 %, leaving at least 10 % headroom. Hodgdon TrailBoss, ReloadSwiss RS 14, Vihtavuori N555 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. ReloadSwiss RS 14, Hodgdon TrailBoss rank at the top here: for .505 Mag. Gibbs with the .505 | 410gr | Impala LW CFN they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, ADI AR 2208, Alliant Reloder- TS 15.5, Alliant Reloder-17 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.