Load Specifications
Load data in caliber .300 Rem. Ultra Mag. with .308 | 155gr | Merlin Virtus bullet and 73 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Accurate MAGPRO, Alliant Reloder-26 and Winchester StaBALL HD.
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% | 56,942 psi | 88% | 2999 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 57,696 psi | 89% | 3041 fps | 100% |
| Accurate MAGPRO | <<locked>> | 92% | 56,057 psi | 86% | 3094 fps | 97.8% |
| ADI AR 2208 | <<locked>> | 82% | 58,262 psi | 90% | 3012 fps | 100% |
| ADI AR 2209 | <<locked>> | 90% | 55,332 psi | 85% | 3045 fps | 99.2% |
| ADI AR 2213 | <<locked>> | 94% | 57,232 psi | 88% | 3107 fps | 98.8% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 51,517 psi | 79% | 2995 fps | 98.3% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 45,992 psi | 71% | 2946 fps | 99.5% |
| Alliant Reloder-16 | <<locked>> | 86% | 55,042 psi | 85% | 3051 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 56,159 psi | 86% | 3058 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 58,552 psi | 90% | 3087 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 94% | 57,232 psi | 88% | 3097 fps | 99.5% |
| Alliant Reloder-23 | <<locked>> | 96% | 58,421 psi | 90% | 3068 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 58,436 psi | 90% | 3127 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 90% | 55,216 psi | 85% | 3097 fps | 100% |
| Bofors RP15 | <<locked>> | 96% | 56,173 psi | 86% | 3077 fps | 99.4% |
| Bofors RP30ᴾ | <<locked>> | 100% | 54,143 psi | 83% | 3061 fps | 98.8% |
| Bofors RP5 | <<locked>> | 94% | 57,232 psi | 88% | 3097 fps | 99.5% |
| Bofors RP7 | <<locked>> | 84% | 56,144 psi | 86% | 2992 fps | 99.7% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 57,000 psi | 88% | 3084 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 84% | 55,724 psi | 86% | 3038 fps | 99.9% |
| Hodgdon H4350 | <<locked>> | 84% | 58,305 psi | 90% | 3058 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 92% | 56,797 psi | 87% | 3038 fps | 98.2% |
| Hodgdon H4831 SC | <<locked>> | 92% | 55,767 psi | 86% | 3022 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 55,303 psi | 85% | 2969 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 57,159 psi | 88% | 3199 fps | 100% |
| Hodgdon Superformance | <<locked>> | 84% | 56,855 psi | 88% | 3074 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,883 psi | 57% | 1978 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 58,247 psi | 90% | 3028 fps | 99.8% |
| IMR 4451 Enduron | <<locked>> | 84% | 57,696 psi | 89% | 3018 fps | 99.9% |
| IMR 4831 | <<locked>> | 88% | 58,218 psi | 90% | 3031 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 57,537 psi | 89% | 3025 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 94% | 54,969 psi | 85% | 3077 fps | 98.5% |
| Lovex S065 | <<locked>> | 86% | 58,363 psi | 90% | 3012 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 56,434 psi | 87% | 3005 fps | 99.9% |
| Lovex S071ᴾ | <<locked>> | 100% | 58,059 psi | 89% | 3015 fps | 100% |
| Norma 204 | <<locked>> | 86% | 55,695 psi | 86% | 3028 fps | 99.1% |
| Norma 217ᴾ | <<locked>> | 100% | 41,394 psi | 64% | 2861 fps | 97.9% |
| Norma MRP | <<locked>> | 92% | 57,232 psi | 88% | 3117 fps | 100% |
| Norma URP | <<locked>> | 86% | 56,057 psi | 86% | 3025 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 55,883 psi | 86% | 3097 fps | 99% |
| Ramshot Hunter | <<locked>> | 86% | 55,259 psi | 85% | 3028 fps | 100% |
| Ramshot Magnum | <<locked>> | 96% | 54,447 psi | 84% | 3022 fps | 99.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,637 psi | 58% | 2024 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 58,160 psi | 90% | 3061 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 56,739 psi | 87% | 3091 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 98% | 54,505 psi | 84% | 3130 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 53,548 psi | 82% | 3071 fps | 97.6% |
| Rottweil R 903 | <<locked>> | 82% | 57,377 psi | 88% | 2992 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 56,260 psi | 87% | 3012 fps | 98.6% |
| Rottweil R 905 | <<locked>> | 92% | 57,972 psi | 89% | 3077 fps | 99.6% |
| Rottweil R 907 | <<locked>> | 84% | 56,144 psi | 86% | 2992 fps | 99.7% |
| Shooters World Long Rifle | <<locked>> | 86% | 58,363 psi | 90% | 3012 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 56,434 psi | 87% | 3005 fps | 99.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 56,971 psi | 88% | 2864 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 57,653 psi | 89% | 2963 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 57,522 psi | 89% | 3071 fps | 99.5% |
| Somchem S355 | <<locked>> | 82% | 57,043 psi | 88% | 2989 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 58,276 psi | 90% | 2999 fps | 98.4% |
| Somchem S365 | <<locked>> | 88% | 56,971 psi | 88% | 3028 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 58,668 psi | 90% | 3048 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 84% | 58,523 psi | 90% | 2956 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 57,928 psi | 89% | 3018 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 58,421 psi | 90% | 3022 fps | 99.8% |
| Vihtavuori N550 | <<locked>> | 86% | 57,217 psi | 88% | 3022 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 56,507 psi | 87% | 3041 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 56,942 psi | 88% | 3114 fps | 98.4% |
| Vihtavuori N565 | <<locked>> | 98% | 57,072 psi | 88% | 3087 fps | 98.7% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 54,259 psi | 84% | 3081 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 58,015 psi | 89% | 2966 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 55,941 psi | 86% | 3045 fps | 99.9% |
| Winchester StaBALL HD | <<locked>> | 96% | 57,334 psi | 88% | 3146 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 54,868 psi | 84% | 2982 fps | 99.2% |
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% | 34,490 psi | 53% | 2592 fps | 96.7% |
| Accurate 4350 | <<locked>> | 80% | 46,528 psi | 72% | 2867 fps | 100% |
| Accurate MAGPRO | 88.6 gr | 88% | 48,370 psi | 74% | 2963 fps | 96% |
| ADI AR 2208 | <<locked>> | 80% | 54,563 psi | 84% | 2956 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 38,856 psi | 60% | 2733 fps | 95.3% |
| ADI AR 2213 | <<locked>> | 86% | 42,917 psi | 66% | 2844 fps | 95.4% |
| ADI AR 2217 | <<locked>> | 94% | 41,539 psi | 64% | 2799 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 92% | 34,838 psi | 54% | 2687 fps | 96.1% |
| Alliant Reloder-16 | <<locked>> | 80% | 44,802 psi | 69% | 2881 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 52,330 psi | 81% | 3002 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 38,870 psi | 60% | 2726 fps | 95.4% |
| Alliant Reloder-22 | <<locked>> | 82% | 37,376 psi | 58% | 2723 fps | 95% |
| Alliant Reloder-23 | <<locked>> | 80% | 33,315 psi | 51% | 2625 fps | 99.3% |
| Alliant Reloder-25 | <<locked>> | 82% | 30,966 psi | 48% | 2582 fps | 95.9% |
| Alliant Reloder-26 | 81.4 gr | 80% | 36,956 psi | 57% | 2762 fps | 98.8% |
| Bofors RP15 | <<locked>> | 86% | 39,755 psi | 61% | 2776 fps | 95.7% |
| Bofors RP30 | <<locked>> | 92% | 40,538 psi | 62% | 2808 fps | 95.4% |
| Bofors RP5 | <<locked>> | 82% | 37,376 psi | 58% | 2723 fps | 95% |
| Bofors RP7 | <<locked>> | 80% | 49,124 psi | 76% | 2877 fps | 98.9% |
| Hodgdon H1000 | <<locked>> | 90% | 39,740 psi | 61% | 2762 fps | 95.4% |
| Hodgdon H414 | <<locked>> | 80% | 48,486 psi | 75% | 2920 fps | 99.2% |
| Hodgdon H4350 | <<locked>> | 80% | 51,039 psi | 79% | 2943 fps | 98.8% |
| Hodgdon H4831 | <<locked>> | 86% | 45,905 psi | 71% | 2851 fps | 95.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 45,049 psi | 69% | 2835 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 42,119 psi | 65% | 2759 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 37,362 psi | 57% | 2795 fps | 95.7% |
| Hodgdon Superformance | <<locked>> | 80% | 48,733 psi | 75% | 2943 fps | 99.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,514 psi | 42% | 1778 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 44,672 psi | 69% | 2805 fps | 98.2% |
| IMR 4451 Enduron | <<locked>> | 80% | 50,618 psi | 78% | 2907 fps | 99.4% |
| IMR 4831 | <<locked>> | 80% | 44,382 psi | 68% | 2815 fps | 99.9% |
| IMR 4955 Enduron | <<locked>> | 84% | 44,324 psi | 68% | 2792 fps | 95.4% |
| IMR 7828 SSC | <<locked>> | 88% | 44,324 psi | 68% | 2884 fps | 96% |
| Lovex S065 | <<locked>> | 80% | 48,080 psi | 74% | 2851 fps | 99.7% |
| Lovex S070 | <<locked>> | 80% | 46,383 psi | 71% | 2838 fps | 99% |
| Lovex S071 | <<locked>> | 82% | 31,560 psi | 49% | 2516 fps | 95.4% |
| Norma 204 | <<locked>> | 80% | 44,947 psi | 69% | 2838 fps | 97.1% |
| Norma 217 | <<locked>> | 96% | 35,839 psi | 55% | 2733 fps | 95.9% |
| Norma MRP | <<locked>> | 80% | 36,463 psi | 56% | 2726 fps | 96.2% |
| Norma URP | <<locked>> | 80% | 45,716 psi | 70% | 2858 fps | 99.9% |
| Ramshot Grand | <<locked>> | 86% | 41,176 psi | 63% | 2825 fps | 95.4% |
| Ramshot Hunter | <<locked>> | 80% | 44,788 psi | 69% | 2851 fps | 99.2% |
| Ramshot Magnum | <<locked>> | 86% | 36,651 psi | 56% | 2690 fps | 95.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,094 psi | 43% | 1818 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 46,934 psi | 72% | 2890 fps | 99.9% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 45,310 psi | 70% | 2907 fps | 99.8% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 34,185 psi | 53% | 2700 fps | 95.6% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 45,513 psi | 70% | 2930 fps | 95.5% |
| Rottweil R 903 | <<locked>> | 80% | 53,577 psi | 82% | 2940 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 42,989 psi | 66% | 2776 fps | 95.6% |
| Rottweil R 905 | <<locked>> | 80% | 38,218 psi | 59% | 2713 fps | 95.4% |
| Rottweil R 907 | <<locked>> | 80% | 49,124 psi | 76% | 2877 fps | 98.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 48,080 psi | 74% | 2851 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 80% | 46,383 psi | 71% | 2838 fps | 99% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 53,432 psi | 82% | 2818 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 47,108 psi | 73% | 2795 fps | 99% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 37,884 psi | 58% | 2707 fps | 95.2% |
| Somchem S355 | <<locked>> | 80% | 53,374 psi | 82% | 2936 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 44,106 psi | 68% | 2759 fps | 95.2% |
| Somchem S365 | <<locked>> | 80% | 42,757 psi | 66% | 2812 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 38,783 psi | 60% | 2694 fps | 96.5% |
| Vihtavuori N150 | <<locked>> | 80% | 51,140 psi | 79% | 2858 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 47,166 psi | 73% | 2851 fps | 100% |
| Vihtavuori N165 | <<locked>> | 82% | 35,911 psi | 55% | 2618 fps | 95.1% |
| Vihtavuori N550 | <<locked>> | 80% | 46,688 psi | 72% | 2854 fps | 99.9% |
| Vihtavuori N555 | <<locked>> | 80% | 37,391 psi | 58% | 2707 fps | 99.2% |
| Vihtavuori N560 | <<locked>> | 86% | 45,847 psi | 71% | 2917 fps | 95.9% |
| Vihtavuori N565 | <<locked>> | 90% | 42,815 psi | 66% | 2831 fps | 95.3% |
| Vihtavuori N568 | <<locked>> | 96% | 46,572 psi | 72% | 2943 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 46,746 psi | 72% | 2808 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 48,660 psi | 75% | 2923 fps | 99.2% |
| Winchester StaBALL HD | 78.2 gr | 80% | 29,588 psi | 46% | 2628 fps | 99.4% |
| Winchester Supreme 780 | <<locked>> | 82% | 38,145 psi | 59% | 2674 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 73 powders for .300 Rem. Ultra Mag. loaded with the .308 | 155gr | Merlin Virtus. Hodgdon Retumbo delivers the highest muzzle velocity at 3,199 fps; across all powders the maximum-charge window runs from 1,978 fps to 3,199 fps. ADI AR 2217 gives the best case fill at 100 %, and 73 of the 73 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 155.0 gr projectile in 0.308" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-25 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. Accurate MAGPRO, Alliant Reloder-26, Winchester StaBALL HD rank at the top here: for .300 Rem. Ultra Mag. with the .308 | 155gr | Merlin Virtus 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.