Load Specifications
Load data in caliber .505 Mag. Gibbs with .505 | 525gr | Woodleigh RN SN bullet and 13 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Somchem S365, Hodgdon Hybrid 100V 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 ≥ 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 |
|---|---|---|---|---|---|---|
| Alliant Reloder-16 | <<locked>> | 88% | 35,331 psi | 90% | 2280 fps | 95.9% |
| Alliant Reloder-17 | <<locked>> | 84% | 34,809 psi | 89% | 2297 fps | 97.6% |
| Alliant Reloder-23 | <<locked>> | 98% | 34,069 psi | 87% | 2287 fps | 97.2% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 34,432 psi | 88% | 2234 fps | 97.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,302 psi | 90% | 1506 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 98% | 34,722 psi | 89% | 1526 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 34,664 psi | 89% | 2303 fps | 99.4% |
| Rottweil R 903 | <<locked>> | 82% | 35,041 psi | 89% | 2228 fps | 97.9% |
| Somchem S365 | <<locked>> | 90% | 33,518 psi | 86% | 2277 fps | 98.6% |
| Vihtavuori N150 | <<locked>> | 82% | 34,200 psi | 87% | 2178 fps | 98.6% |
| Vihtavuori N555 | <<locked>> | 96% | 34,243 psi | 87% | 2306 fps | 96.4% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 34,635 psi | 88% | 2208 fps | 97.6% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 32,271 psi | 82% | 2316 fps | 97.1% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Alliant Reloder-16 | <<locked>> | 86% | 33,315 psi | 85% | 2231 fps | 95.1% |
| Alliant Reloder-17 | <<locked>> | 80% | 30,574 psi | 78% | 2195 fps | 95.8% |
| Alliant Reloder-23 | <<locked>> | 94% | 30,197 psi | 77% | 2188 fps | 95.4% |
| Hodgdon Hybrid 100V | 110.9 gr | 84% | 28,601 psi | 73% | 2096 fps | 95% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,281 psi | 67% | 1345 fps | 100% |
| ReloadSwiss RS 14 | 37.5 gr | 80% | 26,571 psi | 68% | 1378 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 32,532 psi | 83% | 2254 fps | 99% |
| Rottweil R 903 | <<locked>> | 80% | 32,851 psi | 84% | 2178 fps | 97.3% |
| Somchem S365 | 111.3 gr | 82% | 26,092 psi | 67% | 2080 fps | 95.4% |
| Vihtavuori N150 | <<locked>> | 80% | 32,082 psi | 82% | 2133 fps | 98.1% |
| Vihtavuori N555 | <<locked>> | 94% | 32,155 psi | 82% | 2257 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 28,558 psi | 73% | 2064 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 98% | 30,313 psi | 77% | 2260 fps | 95.9% |
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 31 powders for .505 Mag. Gibbs loaded with the .505 | 525gr | Woodleigh RN SN. Alliant Reloder-26 delivers the highest muzzle velocity at 2,349 fps; across all powders the maximum-charge window runs from 1,506 fps to 2,349 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 31 of the 31 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (270 MPa), the top charges use 79–90 %, leaving at least 10 % headroom. Hodgdon TrailBoss, Lovex S071, Winchester StaBALL HD 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. Somchem S365, Hodgdon Hybrid 100V, ReloadSwiss RS 14 rank at the top here: for .505 Mag. Gibbs with the .505 | 525gr | Woodleigh RN SN they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 3100, Alliant Reloder-26, Hodgdon H414 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.