Load Specifications
Load data in caliber .300 Rem. Ultra Mag. with .308 | 185gr | Lapua Mega bullet and 63 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, Vihtavuori N570 and ReloadSwiss RS 76.
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% | 55,419 psi | 85% | 2776 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 58,247 psi | 90% | 2933 fps | 99.4% |
| ADI AR 2209 | <<locked>> | 86% | 56,594 psi | 87% | 2861 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 54,998 psi | 85% | 2871 fps | 99.6% |
| ADI AR 2217 | <<locked>> | 98% | 57,653 psi | 89% | 2900 fps | 99.9% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 54,172 psi | 83% | 2943 fps | 97.7% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 56,188 psi | 86% | 2917 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 56,913 psi | 88% | 2861 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 56,594 psi | 87% | 2851 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 56,289 psi | 87% | 2851 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 55,477 psi | 85% | 2867 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 57,188 psi | 88% | 2831 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 57,595 psi | 89% | 2900 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 58,233 psi | 90% | 2920 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 55,782 psi | 86% | 2927 fps | 97.9% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 51,343 psi | 79% | 2844 fps | 96.4% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 55,767 psi | 86% | 2828 fps | 97.9% |
| Bofors RP15 | <<locked>> | 92% | 58,610 psi | 90% | 2910 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 57,406 psi | 88% | 2913 fps | 99.9% |
| Bofors RP5 | <<locked>> | 88% | 55,477 psi | 85% | 2867 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 55,085 psi | 85% | 2864 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 88% | 57,957 psi | 89% | 2864 fps | 99.5% |
| Hodgdon H4831 SC | <<locked>> | 88% | 56,956 psi | 88% | 2848 fps | 99.4% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 56,884 psi | 88% | 2776 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 56,449 psi | 87% | 2979 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,550 psi | 58% | 1841 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 55,288 psi | 85% | 2785 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 55,912 psi | 86% | 2789 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 58,291 psi | 90% | 2844 fps | 99.6% |
| IMR 7828 SSC | <<locked>> | 90% | 57,261 psi | 88% | 2913 fps | 99.8% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 51,459 psi | 79% | 2838 fps | 99.5% |
| Lovex S070 | <<locked>> | 82% | 57,348 psi | 88% | 2815 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 57,029 psi | 88% | 2799 fps | 100% |
| Norma 204 | <<locked>> | 82% | 56,550 psi | 87% | 2841 fps | 99.9% |
| Norma 217ᴾ | <<locked>> | 100% | 52,620 psi | 81% | 2864 fps | 100% |
| Norma MRP | <<locked>> | 86% | 55,434 psi | 85% | 2881 fps | 100% |
| Norma URP | <<locked>> | 82% | 57,334 psi | 88% | 2828 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 58,581 psi | 90% | 2933 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 82% | 56,550 psi | 87% | 2838 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 57,087 psi | 88% | 2861 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,595 psi | 59% | 1883 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 58,378 psi | 90% | 2897 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 57,682 psi | 89% | 2969 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 57,116 psi | 88% | 2936 fps | 99.4% |
| Rottweil R 904 | <<locked>> | 86% | 57,217 psi | 88% | 2831 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 86% | 55,869 psi | 86% | 2841 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 57,348 psi | 88% | 2815 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 58,001 psi | 89% | 2769 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 55,477 psi | 85% | 2838 fps | 99.9% |
| Somchem S361 | <<locked>> | 86% | 58,755 psi | 90% | 2818 fps | 99.5% |
| Somchem S365 | <<locked>> | 82% | 55,201 psi | 85% | 2782 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 56,420 psi | 87% | 2815 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 56,260 psi | 87% | 2795 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 55,550 psi | 85% | 2812 fps | 96.2% |
| Vihtavuori N550 | <<locked>> | 82% | 58,218 psi | 90% | 2825 fps | 100% |
| Vihtavuori N555 | <<locked>> | 86% | 55,347 psi | 85% | 2812 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 54,897 psi | 84% | 2884 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 92% | 55,869 psi | 86% | 2874 fps | 99.5% |
| Vihtavuori N568 | <<locked>> | 96% | 57,566 psi | 89% | 2936 fps | 99.2% |
| Vihtavuori N570 | <<locked>> | 96% | 54,694 psi | 84% | 2933 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 58,639 psi | 90% | 2766 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 57,261 psi | 88% | 2917 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 56,188 psi | 86% | 2808 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% | 42,250 psi | 65% | 2569 fps | 99.8% |
| Accurate MAGPRO | <<locked>> | 80% | 43,700 psi | 67% | 2684 fps | 96.6% |
| ADI AR 2209 | <<locked>> | 80% | 46,238 psi | 71% | 2694 fps | 99% |
| ADI AR 2213 | <<locked>> | 80% | 41,452 psi | 64% | 2631 fps | 97.1% |
| ADI AR 2217 | <<locked>> | 84% | 35,360 psi | 54% | 2490 fps | 95.3% |
| ADI AR 2218 | <<locked>> | 96% | 46,731 psi | 72% | 2799 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 82% | 30,255 psi | 47% | 2402 fps | 96.2% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 46,601 psi | 72% | 2694 fps | 99.1% |
| Alliant Reloder-16 | <<locked>> | 80% | 53,113 psi | 82% | 2802 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 46,166 psi | 71% | 2687 fps | 99% |
| Alliant Reloder-22 | <<locked>> | 80% | 42,163 psi | 65% | 2641 fps | 98.4% |
| Alliant Reloder-23 | <<locked>> | 80% | 40,901 psi | 63% | 2585 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 35,404 psi | 54% | 2523 fps | 99.4% |
| Alliant Reloder-26 | <<locked>> | 80% | 46,441 psi | 71% | 2746 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 47,819 psi | 74% | 2792 fps | 96% |
| Alliant Reloder-50 | <<locked>> | 98% | 47,543 psi | 73% | 2776 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 45,963 psi | 71% | 2661 fps | 95.6% |
| Bofors RP15 | <<locked>> | 80% | 39,189 psi | 60% | 2575 fps | 97.5% |
| Bofors RP30 | <<locked>> | 82% | 35,302 psi | 54% | 2510 fps | 95.5% |
| Bofors RP5 | <<locked>> | 80% | 42,163 psi | 65% | 2641 fps | 98.4% |
| Hodgdon H1000 | <<locked>> | 80% | 33,533 psi | 52% | 2448 fps | 95.1% |
| Hodgdon H4831 | <<locked>> | 80% | 44,077 psi | 68% | 2635 fps | 97.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 43,294 psi | 67% | 2618 fps | 97% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 49,937 psi | 77% | 2680 fps | 100% |
| Hodgdon Retumbo | 77.4 gr | 80% | 34,519 psi | 53% | 2552 fps | 96.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,137 psi | 43% | 1650 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 51,924 psi | 80% | 2736 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 52,402 psi | 81% | 2740 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 45,223 psi | 70% | 2631 fps | 97.6% |
| IMR 7828 SSC | <<locked>> | 80% | 40,161 psi | 62% | 2615 fps | 96.7% |
| IMR 8133 Enduron | <<locked>> | 90% | 36,390 psi | 56% | 2549 fps | 95.8% |
| Lovex S070 | <<locked>> | 80% | 53,824 psi | 83% | 2762 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 36,318 psi | 56% | 2451 fps | 98.9% |
| Norma 204 | <<locked>> | 80% | 52,765 psi | 81% | 2785 fps | 99.7% |
| Norma 217 | <<locked>> | 84% | 29,747 psi | 46% | 2398 fps | 95.1% |
| Norma MRP | <<locked>> | 80% | 44,773 psi | 69% | 2707 fps | 99.6% |
| Norma URP | <<locked>> | 80% | 53,722 psi | 83% | 2779 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 40,234 psi | 62% | 2625 fps | 97.2% |
| Ramshot Hunter | <<locked>> | 80% | 52,837 psi | 81% | 2785 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 36,085 psi | 56% | 2503 fps | 97.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,848 psi | 44% | 1690 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 54,389 psi | 84% | 2844 fps | 100% |
| ReloadSwiss RS 76 | 82.8 gr | 80% | 33,765 psi | 52% | 2526 fps | 97.8% |
| ReloadSwiss RS 80 | <<locked>> | 86% | 38,885 psi | 60% | 2612 fps | 95.2% |
| Rottweil R 904 | <<locked>> | 80% | 47,065 psi | 72% | 2671 fps | 98.4% |
| Rottweil R 905 | <<locked>> | 80% | 45,701 psi | 70% | 2677 fps | 99.1% |
| Shooters World SW4350 | <<locked>> | 80% | 53,824 psi | 83% | 2762 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 54,244 psi | 83% | 2717 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 45,353 psi | 70% | 2671 fps | 99% |
| Somchem S361 | <<locked>> | 80% | 48,080 psi | 74% | 2657 fps | 98.1% |
| Somchem S365 | <<locked>> | 80% | 51,605 psi | 79% | 2736 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 46,137 psi | 71% | 2654 fps | 99.5% |
| Vihtavuori N165 | <<locked>> | 80% | 40,306 psi | 62% | 2536 fps | 98.4% |
| Vihtavuori N170 | <<locked>> | 92% | 51,880 psi | 80% | 2753 fps | 95.3% |
| Vihtavuori N550 | <<locked>> | 80% | 54,665 psi | 84% | 2776 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 45,513 psi | 70% | 2664 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 44,454 psi | 68% | 2700 fps | 97.4% |
| Vihtavuori N565 | <<locked>> | 80% | 36,956 psi | 57% | 2523 fps | 95.3% |
| Vihtavuori N568 | <<locked>> | 86% | 40,016 psi | 62% | 2625 fps | 95% |
| Vihtavuori N570 | 92.4 gr | 92% | 47,253 psi | 73% | 2805 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 54,708 psi | 84% | 2720 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 38,870 psi | 60% | 2638 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 42,467 psi | 65% | 2585 fps | 98.4% |
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 63 powders for .300 Rem. Ultra Mag. loaded with the .308 | 185gr | Lapua Mega. Hodgdon Retumbo delivers the highest muzzle velocity at 2,979 fps; across all powders the maximum-charge window runs from 1,841 fps to 2,979 fps. ADI AR 2218 gives the best case fill at 100 %, and 63 of the 63 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 185.0 gr projectile in 0.308" calls for a 1:15.5 twist; slower twists will usually not stabilise this weight. ADI AR 2218, ADI AR 2225, Alliant Reloder-50 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, Vihtavuori N570, ReloadSwiss RS 76 rank at the top here: for .300 Rem. Ultra Mag. with the .308 | 185gr | Lapua Mega 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.