Load Specifications
Load data in caliber .300 Rem. Ultra Mag. with .308 | 165gr | Barnes MRX BT bullet and 74 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 76 and IMR 7828 SSC.
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>> | 94% | 58,421 psi | 90% | 2949 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 55,216 psi | 85% | 2933 fps | 100% |
| Accurate MAGPRO | <<locked>> | 92% | 57,493 psi | 88% | 3048 fps | 98.4% |
| ADI AR 2209 | <<locked>> | 90% | 56,550 psi | 87% | 2992 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 94% | 58,740 psi | 90% | 3058 fps | 99.3% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 52,837 psi | 81% | 2953 fps | 98.9% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 47,297 psi | 73% | 2907 fps | 99.9% |
| Alliant Reloder-16 | <<locked>> | 86% | 56,565 psi | 87% | 2995 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 57,783 psi | 89% | 3002 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 90% | 56,159 psi | 86% | 2979 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 94% | 58,769 psi | 90% | 3051 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 94% | 56,086 psi | 86% | 2959 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 98% | 55,883 psi | 86% | 3018 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 90% | 57,014 psi | 88% | 3048 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 56,362 psi | 87% | 2953 fps | 96.7% |
| Bofors RP15 | <<locked>> | 96% | 57,667 psi | 89% | 3031 fps | 99.7% |
| Bofors RP30ᴾ | <<locked>> | 100% | 55,709 psi | 86% | 3018 fps | 99.3% |
| Bofors RP5 | <<locked>> | 94% | 58,769 psi | 90% | 3051 fps | 99.8% |
| Bofors RP7 | <<locked>> | 84% | 57,363 psi | 88% | 2940 fps | 99.9% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 58,552 psi | 90% | 3041 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 84% | 57,029 psi | 88% | 2989 fps | 100% |
| Hodgdon H4350 | <<locked>> | 82% | 55,825 psi | 86% | 2946 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 92% | 58,146 psi | 89% | 2992 fps | 98.7% |
| Hodgdon H4831 SC | <<locked>> | 92% | 57,087 psi | 88% | 2972 fps | 98.6% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 56,797 psi | 87% | 2913 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 98% | 54,737 psi | 84% | 3094 fps | 100% |
| Hodgdon Superformance | <<locked>> | 84% | 58,276 psi | 90% | 3022 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,057 psi | 57% | 1923 fps | 100% |
| IMR 4350 | <<locked>> | 86% | 55,666 psi | 86% | 2920 fps | 99.8% |
| IMR 4451 Enduron | <<locked>> | 82% | 55,172 psi | 85% | 2907 fps | 99.9% |
| IMR 4831 | <<locked>> | 86% | 55,680 psi | 86% | 2923 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 90% | 55,085 psi | 85% | 2917 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 94% | 56,492 psi | 87% | 3031 fps | 99.1% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 42,656 psi | 66% | 2805 fps | 96.7% |
| Lovex S065 | <<locked>> | 84% | 55,869 psi | 86% | 2904 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 57,798 psi | 89% | 2953 fps | 100% |
| Lovex S071 | <<locked>> | 98% | 55,869 psi | 86% | 2917 fps | 100% |
| Norma 204 | <<locked>> | 86% | 57,058 psi | 88% | 2979 fps | 99.5% |
| Norma 217ᴾ | <<locked>> | 100% | 42,917 psi | 66% | 2831 fps | 98.7% |
| Norma MRP | <<locked>> | 90% | 54,621 psi | 84% | 3009 fps | 99.9% |
| Norma URP | <<locked>> | 86% | 57,508 psi | 89% | 2969 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 57,711 psi | 89% | 3054 fps | 99.5% |
| Ramshot Hunter | <<locked>> | 86% | 56,623 psi | 87% | 2976 fps | 100% |
| Ramshot Magnum | <<locked>> | 96% | 56,115 psi | 86% | 2979 fps | 99.9% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,855 psi | 58% | 1965 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 55,521 psi | 85% | 2953 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 58,421 psi | 90% | 3041 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 98% | 56,101 psi | 86% | 3087 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 55,347 psi | 85% | 3038 fps | 98.4% |
| Rottweil R 903 | <<locked>> | 82% | 58,697 psi | 90% | 2933 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 57,508 psi | 89% | 2963 fps | 99.1% |
| Rottweil R 905 | <<locked>> | 90% | 55,695 psi | 86% | 2969 fps | 99.6% |
| Rottweil R 907 | <<locked>> | 84% | 57,363 psi | 88% | 2940 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 84% | 55,869 psi | 86% | 2904 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 57,798 psi | 89% | 2953 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 58,146 psi | 89% | 2805 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 84% | 55,114 psi | 85% | 2858 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 90% | 55,288 psi | 85% | 2966 fps | 99.5% |
| Somchem S355 | <<locked>> | 82% | 58,233 psi | 90% | 2930 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 55,593 psi | 86% | 2894 fps | 98.4% |
| Somchem S365 | <<locked>> | 88% | 58,479 psi | 90% | 2969 fps | 100% |
| Somchem S385 | <<locked>> | 90% | 56,057 psi | 86% | 2940 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 82% | 55,898 psi | 86% | 2848 fps | 100% |
| Vihtavuori N160 | <<locked>> | 84% | 55,492 psi | 85% | 2910 fps | 100% |
| Vihtavuori N165 | <<locked>> | 94% | 55,869 psi | 86% | 2920 fps | 99.8% |
| Vihtavuori N550 | <<locked>> | 86% | 58,523 psi | 90% | 2966 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 58,088 psi | 89% | 2989 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 58,537 psi | 90% | 3064 fps | 99% |
| Vihtavuori N565 | <<locked>> | 98% | 58,639 psi | 90% | 3041 fps | 99.2% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 56,043 psi | 86% | 3041 fps | 98% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 55,434 psi | 85% | 2864 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 57,232 psi | 88% | 2989 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 94% | 54,926 psi | 85% | 3038 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 56,217 psi | 87% | 2933 fps | 99.6% |
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% | 35,636 psi | 55% | 2556 fps | 97.6% |
| Accurate 4350 | <<locked>> | 80% | 47,950 psi | 74% | 2822 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 46,151 psi | 71% | 2854 fps | 95.9% |
| ADI AR 2209 | <<locked>> | 80% | 40,016 psi | 62% | 2694 fps | 96.4% |
| ADI AR 2213 | <<locked>> | 84% | 41,147 psi | 63% | 2743 fps | 95.4% |
| ADI AR 2217 | <<locked>> | 92% | 39,798 psi | 61% | 2700 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 90% | 33,402 psi | 51% | 2592 fps | 96.1% |
| Alliant Reloder-16 | <<locked>> | 80% | 45,919 psi | 71% | 2828 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 53,621 psi | 83% | 2946 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 40,045 psi | 62% | 2690 fps | 96.4% |
| Alliant Reloder-22 | <<locked>> | 80% | 35,810 psi | 55% | 2621 fps | 95% |
| Alliant Reloder-23 | <<locked>> | 80% | 34,432 psi | 53% | 2589 fps | 99.7% |
| Alliant Reloder-25 | <<locked>> | 80% | 29,791 psi | 46% | 2490 fps | 96% |
| Alliant Reloder-26 | <<locked>> | 80% | 38,348 psi | 59% | 2730 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 52,808 psi | 81% | 2890 fps | 95.9% |
| Bofors RP15 | <<locked>> | 84% | 38,305 psi | 59% | 2677 fps | 95.8% |
| Bofors RP30 | <<locked>> | 90% | 38,986 psi | 60% | 2713 fps | 95.4% |
| Bofors RP5 | <<locked>> | 80% | 35,810 psi | 55% | 2621 fps | 95% |
| Bofors RP7 | <<locked>> | 80% | 50,270 psi | 77% | 2825 fps | 99.3% |
| Hodgdon H1000 | <<locked>> | 88% | 37,898 psi | 58% | 2661 fps | 95.3% |
| Hodgdon H414 | <<locked>> | 80% | 49,719 psi | 77% | 2871 fps | 99.6% |
| Hodgdon H4350 | <<locked>> | 80% | 52,185 psi | 80% | 2890 fps | 99.2% |
| Hodgdon H4831 | <<locked>> | 84% | 43,990 psi | 68% | 2749 fps | 95.7% |
| Hodgdon H4831 SC | <<locked>> | 84% | 43,163 psi | 66% | 2733 fps | 95.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 43,134 psi | 66% | 2707 fps | 100% |
| Hodgdon Retumbo | 80.5 gr | 86% | 35,810 psi | 55% | 2697 fps | 95.7% |
| Hodgdon Superformance | <<locked>> | 80% | 50,038 psi | 77% | 2897 fps | 99.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,673 psi | 43% | 1722 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 45,832 psi | 71% | 2756 fps | 98.8% |
| IMR 4451 Enduron | <<locked>> | 80% | 51,793 psi | 80% | 2854 fps | 99.7% |
| IMR 4831 | <<locked>> | 80% | 45,513 psi | 70% | 2766 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 42,395 psi | 65% | 2690 fps | 95.4% |
| IMR 7828 SSC | 80.4 gr | 86% | 42,409 psi | 65% | 2779 fps | 96% |
| IMR 8133 Enduron | <<locked>> | 98% | 39,726 psi | 61% | 2743 fps | 95.6% |
| Lovex S065 | <<locked>> | 80% | 49,211 psi | 76% | 2802 fps | 99.9% |
| Lovex S070 | <<locked>> | 80% | 47,558 psi | 73% | 2789 fps | 99.4% |
| Lovex S071 | <<locked>> | 80% | 30,356 psi | 47% | 2425 fps | 95.5% |
| Norma 204 | <<locked>> | 80% | 46,122 psi | 71% | 2795 fps | 97.9% |
| Norma 217 | <<locked>> | 94% | 34,519 psi | 53% | 2641 fps | 96% |
| Norma MRP | <<locked>> | 80% | 37,666 psi | 58% | 2690 fps | 97.2% |
| Norma URP | <<locked>> | 80% | 46,992 psi | 72% | 2808 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 39,218 psi | 60% | 2720 fps | 95.3% |
| Ramshot Hunter | <<locked>> | 80% | 45,948 psi | 71% | 2802 fps | 99.6% |
| Ramshot Magnum | <<locked>> | 84% | 34,998 psi | 54% | 2592 fps | 95.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,282 psi | 44% | 1765 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 48,095 psi | 74% | 2838 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 46,514 psi | 72% | 2858 fps | 100% |
| ReloadSwiss RS 76 | 84.2 gr | 84% | 32,764 psi | 50% | 2602 fps | 95.5% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 43,337 psi | 67% | 2825 fps | 95.4% |
| Rottweil R 903 | <<locked>> | 80% | 54,984 psi | 85% | 2884 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 41,162 psi | 63% | 2674 fps | 95.6% |
| Rottweil R 905 | <<locked>> | 80% | 39,247 psi | 60% | 2671 fps | 96.4% |
| Rottweil R 907 | <<locked>> | 80% | 50,270 psi | 77% | 2825 fps | 99.3% |
| Shooters World Long Rifle | <<locked>> | 80% | 49,211 psi | 76% | 2802 fps | 99.9% |
| Shooters World SW4350 | <<locked>> | 80% | 47,558 psi | 73% | 2789 fps | 99.4% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 54,505 psi | 84% | 2759 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 48,095 psi | 74% | 2746 fps | 99.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 38,928 psi | 60% | 2667 fps | 96.2% |
| Somchem S355 | <<locked>> | 80% | 54,650 psi | 84% | 2881 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 42,061 psi | 65% | 2654 fps | 95.1% |
| Somchem S365 | <<locked>> | 80% | 44,135 psi | 68% | 2762 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 39,813 psi | 61% | 2654 fps | 97.4% |
| Vihtavuori N150 | <<locked>> | 80% | 52,388 psi | 81% | 2802 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 48,486 psi | 75% | 2805 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 34,476 psi | 53% | 2523 fps | 95.1% |
| Vihtavuori N550 | <<locked>> | 80% | 47,834 psi | 74% | 2805 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 38,435 psi | 59% | 2664 fps | 99.7% |
| Vihtavuori N560 | <<locked>> | 84% | 43,772 psi | 67% | 2808 fps | 95.8% |
| Vihtavuori N565 | <<locked>> | 88% | 41,147 psi | 63% | 2736 fps | 95.3% |
| Vihtavuori N568 | <<locked>> | 94% | 44,643 psi | 69% | 2841 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 47,834 psi | 74% | 2756 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 49,908 psi | 77% | 2874 fps | 99.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 30,748 psi | 47% | 2598 fps | 99.9% |
| Winchester Supreme 780 | <<locked>> | 80% | 36,506 psi | 56% | 2575 fps | 95.3% |
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 74 powders for .300 Rem. Ultra Mag. loaded with the .308 | 165gr | Barnes MRX BT. Hodgdon Retumbo delivers the highest muzzle velocity at 3,094 fps; across all powders the maximum-charge window runs from 1,923 fps to 3,094 fps. ADI AR 2217 gives the best case fill at 100 %, and 74 of the 74 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (448 MPa), the top charges use 57–90 %, leaving at least 10 % headroom. The 165.0 gr projectile in 0.308" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Bofors RP30 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 76, IMR 7828 SSC rank at the top here: for .300 Rem. Ultra Mag. with the .308 | 165gr | Barnes MRX BT 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.