Load Specifications
Load data in caliber .303 Savage with .308 | 115gr | Sierra VarmintKing bullet and 8 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 ≥ 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: 22"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 90% | 34,476 psi | 88% | 2523 fps | 98.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 29,298 psi | 75% | 1640 fps | 100% |
| IMR 4227 | <<locked>> | 82% | 34,882 psi | 89% | 2425 fps | 96.9% |
| Lovex S053 | <<locked>> | 82% | 33,794 psi | 86% | 2408 fps | 99.3% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 28,674 psi | 73% | 1677 fps | 100% |
| ReloadSwiss RS 36 | <<locked>> | 82% | 33,475 psi | 85% | 2438 fps | 96.3% |
| SNPE Vectan BA6 1/2 | <<locked>> | 86% | 35,433 psi | 90% | 2336 fps | 100% |
| Vihtavuori N120 | <<locked>> | 90% | 34,795 psi | 89% | 2497 fps | 99.1% |
Start Load - Barrel Length: 22"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 82% | 27,035 psi | 69% | 2333 fps | 95.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 21,306 psi | 54% | 1463 fps | 100% |
| IMR 4227 | <<locked>> | 80% | 32,764 psi | 84% | 2379 fps | 96.3% |
| Lovex S053 | <<locked>> | 80% | 31,807 psi | 81% | 2362 fps | 98.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 21,016 psi | 54% | 1499 fps | 100% |
| ReloadSwiss RS 36 | <<locked>> | 80% | 31,531 psi | 81% | 2392 fps | 95.6% |
| SNPE Vectan BA6 1/2 | <<locked>> | 80% | 30,052 psi | 77% | 2228 fps | 100% |
| Vihtavuori N120 | <<locked>> | 80% | 25,846 psi | 66% | 2267 fps | 96.3% |
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 16 powders for .303 Savage loaded with the .308 | 115gr | Sierra VarmintKing. ADI AR 2207 delivers the highest muzzle velocity at 2,523 fps; across all powders the maximum-charge window runs from 1,640 fps to 2,523 fps. Accurate 2015 gives the best case fill at 100 %, and 16 of the 16 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (270 MPa), the top charges use 73–90 %, leaving at least 10 % headroom. The 115.0 gr projectile in 0.308" calls for a 1:14.5 twist; slower twists will usually not stabilise this weight. Accurate 2015, Alliant AR-Comp, 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, Accurate 1680, Accurate 2015, Alliant AR-Comp 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.