Load Specifications
Load data in caliber .300 Rem. Ultra Mag. with .308 | 205gr | Sierra GameKing bullet and 56 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ReloadSwiss RS 80 and Vihtavuori N570.
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 3100 | <<locked>> | 88% | 57,653 psi | 89% | 2687 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 56,652 psi | 87% | 2792 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 86% | 58,769 psi | 90% | 2772 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 57,348 psi | 88% | 2789 fps | 100% |
| ADI AR 2217 | <<locked>> | 96% | 56,115 psi | 86% | 2766 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 56,724 psi | 87% | 2881 fps | 99% |
| ADI AR 2225 | <<locked>> | 98% | 54,998 psi | 85% | 2782 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 84% | 55,288 psi | 85% | 2717 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 58,233 psi | 90% | 2759 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 57,783 psi | 89% | 2782 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 55,825 psi | 86% | 2694 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 56,260 psi | 87% | 2762 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 56,463 psi | 87% | 2772 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 58,581 psi | 90% | 2858 fps | 99% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 53,998 psi | 83% | 2785 fps | 97.9% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 57,696 psi | 89% | 2746 fps | 98.9% |
| Bofors RP15 | <<locked>> | 90% | 56,956 psi | 88% | 2769 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 56,028 psi | 86% | 2779 fps | 100% |
| Bofors RP5 | <<locked>> | 88% | 57,783 psi | 89% | 2782 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 57,551 psi | 89% | 2782 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 56,217 psi | 87% | 2723 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 55,245 psi | 85% | 2707 fps | 99.6% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 55,303 psi | 85% | 2631 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 55,332 psi | 85% | 2844 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,739 psi | 58% | 1749 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 57,145 psi | 88% | 2694 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 57,943 psi | 89% | 2694 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 56,608 psi | 87% | 2703 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 88% | 55,593 psi | 86% | 2769 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 94% | 58,798 psi | 90% | 2700 fps | 96.1% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 53,940 psi | 83% | 2766 fps | 99.9% |
| Lovex S071 | <<locked>> | 92% | 55,796 psi | 86% | 2664 fps | 100% |
| Norma 204 | <<locked>> | 82% | 58,566 psi | 90% | 2749 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 55,347 psi | 85% | 2789 fps | 100% |
| Norma MRP | <<locked>> | 86% | 57,899 psi | 89% | 2795 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 56,927 psi | 88% | 2789 fps | 100% |
| Ramshot Hunter | <<locked>> | 82% | 58,595 psi | 90% | 2743 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 55,434 psi | 85% | 2723 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,711 psi | 60% | 1788 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 56,144 psi | 86% | 2828 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 55,535 psi | 85% | 2802 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 55,564 psi | 86% | 2690 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 86% | 58,059 psi | 89% | 2753 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 57,667 psi | 89% | 2749 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 57,014 psi | 88% | 2684 fps | 99.7% |
| Somchem S365 | <<locked>> | 82% | 57,493 psi | 88% | 2687 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 58,421 psi | 90% | 2720 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 58,494 psi | 90% | 2710 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 57,682 psi | 89% | 2736 fps | 97.5% |
| Vihtavuori N555 | <<locked>> | 86% | 57,754 psi | 89% | 2720 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 57,305 psi | 88% | 2802 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 92% | 58,247 psi | 90% | 2792 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 94% | 56,115 psi | 86% | 2805 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 96% | 57,261 psi | 88% | 2861 fps | 98.5% |
| Winchester StaBALL HD | <<locked>> | 88% | 56,130 psi | 86% | 2776 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 58,421 psi | 90% | 2723 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 43,990 psi | 68% | 2490 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 45,701 psi | 70% | 2615 fps | 98% |
| ADI AR 2209 | <<locked>> | 80% | 47,993 psi | 74% | 2612 fps | 99.7% |
| ADI AR 2213 | <<locked>> | 80% | 43,207 psi | 66% | 2559 fps | 98.4% |
| ADI AR 2217 | <<locked>> | 80% | 32,227 psi | 50% | 2320 fps | 95% |
| ADI AR 2218 | <<locked>> | 94% | 45,339 psi | 70% | 2677 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 29,602 psi | 46% | 2293 fps | 97.1% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 48,327 psi | 74% | 2612 fps | 99.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 47,863 psi | 74% | 2605 fps | 99.7% |
| Alliant Reloder-22 | <<locked>> | 80% | 43,976 psi | 68% | 2566 fps | 99.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 42,786 psi | 66% | 2507 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 37,028 psi | 57% | 2454 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 80% | 48,631 psi | 75% | 2664 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 43,279 psi | 67% | 2605 fps | 95.6% |
| Alliant Reloder-50 | <<locked>> | 96% | 46,311 psi | 71% | 2654 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 41,814 psi | 64% | 2480 fps | 95.2% |
| Bofors RP15 | <<locked>> | 80% | 40,959 psi | 63% | 2507 fps | 98.7% |
| Bofors RP30 | <<locked>> | 80% | 34,563 psi | 53% | 2392 fps | 96.3% |
| Bofors RP5 | <<locked>> | 80% | 43,976 psi | 68% | 2566 fps | 99.3% |
| Hodgdon H1000 | <<locked>> | 80% | 35,114 psi | 54% | 2392 fps | 97% |
| Hodgdon H4831 | <<locked>> | 80% | 45,803 psi | 70% | 2559 fps | 98.4% |
| Hodgdon H4831 SC | <<locked>> | 80% | 44,976 psi | 69% | 2543 fps | 98.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 51,837 psi | 80% | 2585 fps | 100% |
| Hodgdon Retumbo | 74.9 gr | 80% | 36,172 psi | 56% | 2497 fps | 98.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,311 psi | 44% | 1565 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 53,563 psi | 82% | 2641 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 54,433 psi | 84% | 2648 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 46,717 psi | 72% | 2549 fps | 98.6% |
| IMR 7828 SSC | <<locked>> | 80% | 42,119 psi | 65% | 2546 fps | 98.2% |
| IMR 7977 Enduron | <<locked>> | 92% | 55,216 psi | 85% | 2648 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 86% | 33,417 psi | 51% | 2382 fps | 95.7% |
| Lovex S071 | <<locked>> | 80% | 37,985 psi | 58% | 2382 fps | 99.6% |
| Norma 204 | <<locked>> | 80% | 54,781 psi | 84% | 2697 fps | 100% |
| Norma 217 | <<locked>> | 82% | 29,269 psi | 45% | 2293 fps | 96.1% |
| Norma MRP | <<locked>> | 80% | 46,905 psi | 72% | 2635 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 42,163 psi | 65% | 2556 fps | 98.6% |
| Ramshot Hunter | <<locked>> | 80% | 54,897 psi | 84% | 2697 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 38,072 psi | 59% | 2444 fps | 98.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,080 psi | 45% | 1604 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 35,549 psi | 55% | 2474 fps | 99.2% |
| ReloadSwiss RS 80 | 84.9 gr | 84% | 37,927 psi | 58% | 2490 fps | 96% |
| Rottweil R 904 | <<locked>> | 80% | 48,805 psi | 75% | 2589 fps | 99.3% |
| Rottweil R 905 | <<locked>> | 80% | 47,630 psi | 73% | 2598 fps | 99.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 47,282 psi | 73% | 2592 fps | 99.7% |
| Somchem S361 | <<locked>> | 80% | 49,806 psi | 77% | 2579 fps | 99% |
| Somchem S365 | <<locked>> | 80% | 53,635 psi | 83% | 2638 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 47,906 psi | 74% | 2572 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 41,916 psi | 65% | 2461 fps | 99.3% |
| Vihtavuori N170 | <<locked>> | 88% | 47,137 psi | 73% | 2569 fps | 95% |
| Vihtavuori N555 | <<locked>> | 80% | 47,485 psi | 73% | 2579 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 46,528 psi | 72% | 2631 fps | 98.7% |
| Vihtavuori N565 | <<locked>> | 80% | 38,740 psi | 60% | 2464 fps | 97% |
| Vihtavuori N568 | <<locked>> | 84% | 39,088 psi | 60% | 2507 fps | 95.8% |
| Vihtavuori N570 | 85.6 gr | 88% | 42,975 psi | 66% | 2618 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 80% | 41,321 psi | 64% | 2566 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 44,208 psi | 68% | 2510 fps | 99.3% |
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 56 powders for .300 Rem. Ultra Mag. loaded with the .308 | 205gr | Sierra GameKing. ADI AR 2218 delivers the highest muzzle velocity at 2,881 fps; across all powders the maximum-charge window runs from 1,749 fps to 2,881 fps. ADI AR 2218 gives the best case fill at 100 %, and 56 of the 56 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (448 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 205.0 gr projectile in 0.308" calls for a 1:13.0 twist; slower twists will usually not stabilise this weight. ADI AR 2218, Alliant Reloder-50, 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. Hodgdon Retumbo, ReloadSwiss RS 80, Vihtavuori N570 rank at the top here: for .300 Rem. Ultra Mag. with the .308 | 205gr | Sierra GameKing 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.