Load Specifications
Load data in caliber .300 WSM with .308 | 180gr | Swift Scirocco bullet and 22 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: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 82% | 55,941 psi | 88% | 2671 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 55,114 psi | 86% | 2697 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 56,550 psi | 89% | 2762 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 57,159 psi | 90% | 2759 fps | 98.3% |
| Accurate 3100ᴾ | <<locked>> | 100% | 45,701 psi | 72% | 2674 fps | 98% |
| Accurate 4064 | <<locked>> | 88% | 55,158 psi | 86% | 2746 fps | 100% |
| Accurate 4350 | <<locked>> | 96% | 55,419 psi | 87% | 2844 fps | 99.9% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 54,839 psi | 86% | 2795 fps | 99.9% |
| IMR 3031 | <<locked>> | 84% | 55,898 psi | 88% | 2766 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 55,506 psi | 87% | 2762 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 86% | 55,129 psi | 86% | 2746 fps | 98.6% |
| IMR 4350 | <<locked>> | 98% | 57,377 psi | 90% | 2825 fps | 98.6% |
| IMR 4451 Enduron | <<locked>> | 92% | 55,216 psi | 87% | 2772 fps | 98.6% |
| IMR 4831 | <<locked>> | 98% | 55,651 psi | 87% | 2831 fps | 100% |
| IMR 4895 | <<locked>> | 86% | 54,839 psi | 86% | 2802 fps | 100% |
| Norma 201 | <<locked>> | 86% | 57,246 psi | 90% | 2772 fps | 100% |
| Norma 202 | <<locked>> | 84% | 54,259 psi | 85% | 2720 fps | 100% |
| Norma 203B | <<locked>> | 88% | 56,188 psi | 88% | 2812 fps | 100% |
| Norma 204 | <<locked>> | 96% | 54,549 psi | 85% | 2822 fps | 97.1% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 56,536 psi | 89% | 2799 fps | 100% |
| Winchester 748 | <<locked>> | 82% | 54,549 psi | 85% | 2772 fps | 100% |
| Winchester 760 | <<locked>> | 94% | 54,418 psi | 85% | 2841 fps | 98.7% |
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 52,663 psi | 83% | 2628 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 45,513 psi | 71% | 2562 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 52,721 psi | 83% | 2710 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 44,106 psi | 69% | 2546 fps | 95.7% |
| Accurate 3100 | <<locked>> | 94% | 37,275 psi | 58% | 2513 fps | 95.8% |
| Accurate 4064 | <<locked>> | 80% | 43,076 psi | 68% | 2566 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 31,981 psi | 50% | 2405 fps | 95.8% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 47,834 psi | 75% | 2684 fps | 99.5% |
| IMR 3031 | <<locked>> | 80% | 49,052 psi | 77% | 2667 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 43,424 psi | 68% | 2566 fps | 99.3% |
| IMR 4166 Enduron | <<locked>> | 80% | 45,788 psi | 72% | 2589 fps | 97% |
| IMR 4350 | <<locked>> | 88% | 42,105 psi | 66% | 2569 fps | 95.5% |
| IMR 4451 Enduron | <<locked>> | 82% | 40,654 psi | 64% | 2516 fps | 95.5% |
| IMR 4831 | <<locked>> | 80% | 30,922 psi | 48% | 2365 fps | 95.4% |
| IMR 4895 | <<locked>> | 80% | 45,353 psi | 71% | 2651 fps | 99.8% |
| Norma 201 | <<locked>> | 80% | 47,645 psi | 75% | 2628 fps | 100% |
| Norma 202 | <<locked>> | 80% | 47,892 psi | 75% | 2628 fps | 100% |
| Norma 203B | <<locked>> | 80% | 43,598 psi | 68% | 2608 fps | 99.6% |
| Norma 204 | <<locked>> | 92% | 47,529 psi | 74% | 2707 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 33,011 psi | 52% | 2382 fps | 98.1% |
| Winchester 748 | <<locked>> | 80% | 50,879 psi | 80% | 2720 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 39,117 psi | 61% | 2566 fps | 95.3% |
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 22 powders for .300 WSM loaded with the .308 | 180gr | Swift Scirocco. Accurate 4350 delivers the highest muzzle velocity at 2,844 fps; across all powders the maximum-charge window runs from 2,671 fps to 2,844 fps. Accurate 3100 gives the best case fill at 100 %, and 22 of the 22 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 72–90 %, leaving at least 10 % headroom. The 180.0 gr projectile in 0.308" calls for a 1:11.0 twist; slower twists will usually not stabilise this weight. Accurate 3100 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. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.