Load Specifications
Load data in caliber 8 x 58 R with .318 | 165gr | Impala LW CFN bullet and 3 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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 23.62"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Alliant AR-Comp | <<locked>> | 84% | 27,688 psi | 87% | 2077 fps | 97% |
| Hodgdon TrailBoss | <<locked>> | 92% | 28,863 psi | 90% | 1375 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 92% | 28,776 psi | 90% | 1407 fps | 100% |
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 |
|---|---|---|---|---|---|---|
| Alliant AR-Comp | <<locked>> | 80% | 24,860 psi | 78% | 1991 fps | 95.4% |
| Hodgdon TrailBoss | 9.1 gr | 80% | 23,931 psi | 75% | 1276 fps | 100% |
| ReloadSwiss RS 14 | 9.3 gr | 80% | 23,946 psi | 75% | 1312 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
This overview compares 3 powders for 8 x 58 R loaded with the .318 | 165gr | Impala LW CFN. Alliant AR-Comp delivers the highest muzzle velocity at 2,077 fps; across all powders the maximum-charge window runs from 1,375 fps to 2,077 fps. Hodgdon TrailBoss gives the best case fill at 92 %, and 3 of the 3 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (220 MPa), the top charges use 87–90 %, leaving at least 10 % headroom. The 165.0 gr projectile in 0.318" calls for a 1:13.5 twist; slower twists will usually not stabilise this weight. ReloadSwiss RS 14, Hodgdon TrailBoss rank at the top here: for 8 x 58 R with the .318 | 165gr | Impala LW CFN 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.