Load Specifications
Load data in caliber .303 Savage with .308 | 150gr | Speer Grand Slam bullet and 12 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant AR-Comp, Alliant Reloder-10x and Vihtavuori N130.
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 |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 94% | 35,012 psi | 89% | 2224 fps | 96.6% |
| ADI AR 2207 | <<locked>> | 82% | 34,214 psi | 87% | 2195 fps | 99.9% |
| Alliant AR-Comp | <<locked>> | 96% | 34,505 psi | 88% | 2280 fps | 98.7% |
| Alliant Reloder-10x | <<locked>> | 88% | 33,953 psi | 87% | 2215 fps | 97.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 31,198 psi | 80% | 1447 fps | 100% |
| IMR 4198 | <<locked>> | 86% | 34,664 psi | 89% | 2175 fps | 98.4% |
| Norma 200 | <<locked>> | 84% | 33,881 psi | 87% | 2201 fps | 98.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 30,835 psi | 79% | 1480 fps | 100% |
| Vihtavuori N120 | <<locked>> | 82% | 34,461 psi | 88% | 2169 fps | 100% |
| Vihtavuori N130 | <<locked>> | 90% | 35,215 psi | 90% | 2185 fps | 97.5% |
| Vihtavuori N133 | <<locked>> | 94% | 34,432 psi | 88% | 2172 fps | 96% |
| Vihtavuori N135ᴾ | <<locked>> | 100% | 33,431 psi | 85% | 2234 fps | 96.1% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 22"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 90% | 31,024 psi | 79% | 2142 fps | 95.2% |
| ADI AR 2207 | <<locked>> | 80% | 32,155 psi | 82% | 2152 fps | 99.6% |
| Alliant AR-Comp | 26.6 gr | 86% | 25,744 psi | 66% | 2060 fps | 95.1% |
| Alliant Reloder-10x | 24.7 gr | 82% | 28,282 psi | 72% | 2087 fps | 95.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 22,742 psi | 58% | 1286 fps | 100% |
| IMR 4198 | <<locked>> | 80% | 29,240 psi | 75% | 2054 fps | 96.7% |
| Norma 200 | <<locked>> | 80% | 30,066 psi | 77% | 2116 fps | 97.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 22,626 psi | 58% | 1319 fps | 100% |
| Vihtavuori N120 | <<locked>> | 80% | 32,387 psi | 83% | 2129 fps | 100% |
| Vihtavuori N130 | 25.4 gr | 84% | 29,428 psi | 75% | 2060 fps | 95.5% |
| Vihtavuori N133 | <<locked>> | 92% | 32,503 psi | 83% | 2133 fps | 95.3% |
| Vihtavuori N135 | <<locked>> | 98% | 31,546 psi | 81% | 2195 fps | 95.4% |
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 36 powders for .303 Savage loaded with the .308 | 150gr | Speer Grand Slam. IMR 3031 delivers the highest muzzle velocity at 2,290 fps; across all powders the maximum-charge window runs from 1,447 fps to 2,290 fps. Accurate 2495 gives the best case fill at 100 %, and 36 of the 36 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (270 MPa), the top charges use 77–90 %, leaving at least 10 % headroom. The 150.0 gr projectile in 0.308" calls for a 1:16.0 twist; slower twists will usually not stabilise this weight. Accurate 2495, Hodgdon TrailBoss, Lovex D073.6 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. Alliant AR-Comp, Alliant Reloder-10x, Vihtavuori N130 rank at the top here: for .303 Savage with the .308 | 150gr | Speer Grand Slam they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 2460, Accurate 2520, Accurate LT-30 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.