Load Specifications
Load data in caliber .303 Savage with .308 | 135gr | Sierra SP SSPistol bullet and 10 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant AR-Comp, IMR 4198 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: 22"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 84% | 34,011 psi | 87% | 2326 fps | 99.4% |
| Alliant AR-Comp | <<locked>> | 98% | 34,403 psi | 88% | 2402 fps | 97.6% |
| Alliant Reloder-10x | <<locked>> | 90% | 33,779 psi | 86% | 2343 fps | 96.4% |
| Alliant Reloder-7 | <<locked>> | 82% | 33,518 psi | 86% | 2270 fps | 96.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 30,603 psi | 78% | 1532 fps | 100% |
| IMR 4198 | <<locked>> | 88% | 34,722 psi | 89% | 2303 fps | 97.4% |
| Norma 200 | <<locked>> | 86% | 33,649 psi | 86% | 2326 fps | 97.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 30,168 psi | 77% | 1568 fps | 100% |
| Vihtavuori N120 | <<locked>> | 84% | 34,258 psi | 87% | 2300 fps | 99.9% |
| Vihtavuori N130 | <<locked>> | 92% | 35,041 psi | 89% | 2310 fps | 96.4% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 22"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| ADI AR 2207 | <<locked>> | 80% | 30,066 psi | 77% | 2241 fps | 98.7% |
| Alliant AR-Comp | 29.2 gr | 92% | 28,732 psi | 73% | 2257 fps | 95.2% |
| Alliant Reloder-10x | <<locked>> | 88% | 31,836 psi | 81% | 2297 fps | 95.7% |
| Alliant Reloder-7 | <<locked>> | 80% | 31,604 psi | 81% | 2228 fps | 96.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 22,481 psi | 57% | 1368 fps | 100% |
| IMR 4198 | 24.1 gr | 82% | 29,196 psi | 75% | 2172 fps | 95.4% |
| Norma 200 | <<locked>> | 80% | 27,963 psi | 71% | 2192 fps | 95% |
| ReloadSwiss RS 14 | 9 gr | 80% | 21,973 psi | 56% | 1394 fps | 100% |
| Vihtavuori N120 | <<locked>> | 80% | 30,327 psi | 77% | 2215 fps | 99.5% |
| Vihtavuori N130 | <<locked>> | 90% | 32,779 psi | 84% | 2260 fps | 95.6% |
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 10 powders for .303 Savage loaded with the .308 | 135gr | Sierra SP SSPistol. Alliant AR-Comp delivers the highest muzzle velocity at 2,402 fps; across all powders the maximum-charge window runs from 1,532 fps to 2,402 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 10 of the 10 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (270 MPa), the top charges use 77–89 %, leaving at least 11 % headroom. The 135.0 gr projectile in 0.308" calls for a 1:16.5 twist; slower twists will usually not stabilise this weight. Hodgdon TrailBoss, ReloadSwiss RS 14 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, IMR 4198, ReloadSwiss RS 14 rank at the top here: for .303 Savage with the .308 | 135gr | Sierra SP SSPistol 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.