Load Specifications
Load data in caliber .300 Rem. Ultra Mag. with .308 | 155gr | Frontier RSBT bullet and 74 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Accurate MAGPRO, Ramshot Grand and Alliant Reloder-26.
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% | 57,406 psi | 88% | 3005 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 58,044 psi | 89% | 3045 fps | 100% |
| Accurate MAGPRO | <<locked>> | 92% | 56,043 psi | 86% | 3094 fps | 97.7% |
| ADI AR 2208 | <<locked>> | 82% | 58,349 psi | 90% | 3009 fps | 100% |
| ADI AR 2209 | <<locked>> | 90% | 55,259 psi | 85% | 3041 fps | 99.2% |
| ADI AR 2213 | <<locked>> | 94% | 57,029 psi | 88% | 3100 fps | 98.7% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 51,532 psi | 79% | 2992 fps | 98.2% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 46,195 psi | 71% | 2949 fps | 99.5% |
| Alliant Reloder-16 | <<locked>> | 86% | 54,969 psi | 85% | 3048 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 56,188 psi | 86% | 3058 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 58,523 psi | 90% | 3084 fps | 99.5% |
| Alliant Reloder-22 | <<locked>> | 94% | 57,145 psi | 88% | 3094 fps | 99.5% |
| Alliant Reloder-23 | <<locked>> | 96% | 58,479 psi | 90% | 3064 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 58,349 psi | 90% | 3127 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 90% | 55,216 psi | 85% | 3097 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 96% | 58,798 psi | 90% | 3051 fps | 96.6% |
| Bofors RP15 | <<locked>> | 96% | 56,304 psi | 87% | 3077 fps | 99.3% |
| Bofors RP30ᴾ | <<locked>> | 100% | 54,273 psi | 84% | 3068 fps | 98.8% |
| Bofors RP5 | <<locked>> | 94% | 57,145 psi | 88% | 3094 fps | 99.5% |
| Bofors RP7 | <<locked>> | 84% | 56,246 psi | 87% | 2989 fps | 99.6% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 57,000 psi | 88% | 3084 fps | 99.4% |
| Hodgdon H414 | <<locked>> | 84% | 55,869 psi | 86% | 3041 fps | 99.8% |
| Hodgdon H4350 | <<locked>> | 84% | 58,320 psi | 90% | 3054 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 92% | 56,811 psi | 87% | 3035 fps | 98.1% |
| Hodgdon H4831 SC | <<locked>> | 92% | 55,579 psi | 86% | 3018 fps | 97.9% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 55,376 psi | 85% | 2969 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 57,087 psi | 88% | 3199 fps | 100% |
| Hodgdon Superformance | <<locked>> | 84% | 56,869 psi | 88% | 3074 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,072 psi | 57% | 1975 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 58,320 psi | 90% | 3028 fps | 99.8% |
| IMR 4451 Enduron | <<locked>> | 84% | 57,653 psi | 89% | 3012 fps | 99.9% |
| IMR 4831 | <<locked>> | 88% | 58,479 psi | 90% | 3035 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 57,725 psi | 89% | 3022 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 94% | 54,998 psi | 85% | 3077 fps | 98.5% |
| Lovex S065 | <<locked>> | 86% | 58,523 psi | 90% | 3012 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 56,826 psi | 87% | 3009 fps | 99.9% |
| Lovex S071ᴾ | <<locked>> | 100% | 58,421 psi | 90% | 3018 fps | 100% |
| Norma 204 | <<locked>> | 86% | 55,593 psi | 86% | 3025 fps | 99.1% |
| Norma 217ᴾ | <<locked>> | 100% | 41,640 psi | 64% | 2871 fps | 98% |
| Norma MRP | <<locked>> | 92% | 57,159 psi | 88% | 3117 fps | 99.9% |
| Norma URP | <<locked>> | 86% | 56,333 psi | 87% | 3028 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 55,738 psi | 86% | 3094 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 86% | 55,245 psi | 85% | 3028 fps | 100% |
| Ramshot Magnum | <<locked>> | 96% | 54,520 psi | 84% | 3022 fps | 99.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,855 psi | 58% | 2021 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 58,436 psi | 90% | 3064 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 56,884 psi | 88% | 3094 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 58,581 psi | 90% | 3196 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 53,664 psi | 83% | 3077 fps | 97.6% |
| Rottweil R 903 | <<locked>> | 82% | 57,783 psi | 89% | 2995 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 56,347 psi | 87% | 3009 fps | 98.5% |
| Rottweil R 905 | <<locked>> | 92% | 58,175 psi | 90% | 3074 fps | 99.5% |
| Rottweil R 907 | <<locked>> | 84% | 56,246 psi | 87% | 2989 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 86% | 58,523 psi | 90% | 3012 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 56,826 psi | 87% | 3009 fps | 99.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 57,246 psi | 88% | 2864 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 57,914 psi | 89% | 2963 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 57,754 psi | 89% | 3071 fps | 99.5% |
| Somchem S355 | <<locked>> | 82% | 57,319 psi | 88% | 2989 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 58,218 psi | 90% | 2995 fps | 98.3% |
| Somchem S365 | <<locked>> | 88% | 57,145 psi | 88% | 3028 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 58,595 psi | 90% | 3041 fps | 99.8% |
| Vihtavuori N150 | <<locked>> | 84% | 58,610 psi | 90% | 2953 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 58,001 psi | 89% | 3015 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 58,334 psi | 90% | 3018 fps | 99.7% |
| Vihtavuori N550 | <<locked>> | 86% | 57,464 psi | 88% | 3022 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 56,695 psi | 87% | 3041 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 56,826 psi | 87% | 3110 fps | 98.3% |
| Vihtavuori N565 | <<locked>> | 98% | 57,276 psi | 88% | 3087 fps | 98.6% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 54,215 psi | 83% | 3077 fps | 97.1% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 57,972 psi | 89% | 2966 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 56,057 psi | 86% | 3045 fps | 99.9% |
| Winchester StaBALL HD | <<locked>> | 96% | 57,217 psi | 88% | 3150 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 54,998 psi | 85% | 2982 fps | 99.1% |
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% | 35,317 psi | 54% | 2608 fps | 96.9% |
| Accurate 4350 | <<locked>> | 80% | 47,224 psi | 73% | 2877 fps | 100% |
| Accurate MAGPRO | 87.1 gr | 88% | 48,588 psi | 75% | 2966 fps | 96% |
| ADI AR 2208 | <<locked>> | 80% | 54,781 psi | 84% | 2956 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 39,117 psi | 60% | 2736 fps | 95.4% |
| ADI AR 2213 | <<locked>> | 86% | 43,134 psi | 66% | 2848 fps | 95.4% |
| ADI AR 2217 | <<locked>> | 94% | 41,771 psi | 64% | 2802 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 92% | 35,215 psi | 54% | 2697 fps | 96.2% |
| Alliant Reloder-16 | <<locked>> | 80% | 44,918 psi | 69% | 2881 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 52,388 psi | 81% | 3002 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 39,334 psi | 61% | 2733 fps | 95.5% |
| Alliant Reloder-22 | <<locked>> | 82% | 37,637 psi | 58% | 2726 fps | 95% |
| Alliant Reloder-23 | <<locked>> | 80% | 33,707 psi | 52% | 2635 fps | 99.4% |
| Alliant Reloder-25 | <<locked>> | 82% | 31,459 psi | 48% | 2595 fps | 96.1% |
| Alliant Reloder-26 | 80 gr | 80% | 37,333 psi | 57% | 2772 fps | 98.9% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 55,114 psi | 85% | 2992 fps | 95.8% |
| Bofors RP15 | <<locked>> | 86% | 40,205 psi | 62% | 2782 fps | 95.8% |
| Bofors RP30 | <<locked>> | 92% | 40,799 psi | 63% | 2815 fps | 95.5% |
| Bofors RP5 | <<locked>> | 82% | 37,637 psi | 58% | 2726 fps | 95% |
| Bofors RP7 | <<locked>> | 80% | 49,559 psi | 76% | 2881 fps | 98.9% |
| Hodgdon H1000 | <<locked>> | 90% | 39,972 psi | 62% | 2766 fps | 95.4% |
| Hodgdon H414 | <<locked>> | 80% | 48,762 psi | 75% | 2923 fps | 99.2% |
| Hodgdon H4350 | <<locked>> | 80% | 51,198 psi | 79% | 2940 fps | 98.7% |
| Hodgdon H4831 | <<locked>> | 86% | 46,079 psi | 71% | 2851 fps | 95.6% |
| Hodgdon H4831 SC | <<locked>> | 86% | 45,252 psi | 70% | 2838 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 42,380 psi | 65% | 2762 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 37,594 psi | 58% | 2802 fps | 95.7% |
| Hodgdon Superformance | <<locked>> | 80% | 48,718 psi | 75% | 2943 fps | 99.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,688 psi | 43% | 1775 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 44,875 psi | 69% | 2802 fps | 98.1% |
| IMR 4451 Enduron | <<locked>> | 80% | 50,923 psi | 78% | 2907 fps | 99.4% |
| IMR 4831 | <<locked>> | 80% | 44,788 psi | 69% | 2818 fps | 99.9% |
| IMR 4955 Enduron | <<locked>> | 84% | 44,454 psi | 68% | 2792 fps | 95.4% |
| IMR 7828 SSC | <<locked>> | 88% | 44,570 psi | 69% | 2887 fps | 96% |
| Lovex S065 | <<locked>> | 80% | 48,370 psi | 74% | 2854 fps | 99.7% |
| Lovex S070 | <<locked>> | 80% | 46,731 psi | 72% | 2841 fps | 99% |
| Lovex S071 | <<locked>> | 82% | 32,358 psi | 50% | 2533 fps | 95.8% |
| Norma 204 | <<locked>> | 80% | 45,237 psi | 70% | 2841 fps | 97.1% |
| Norma 217 | <<locked>> | 96% | 36,274 psi | 56% | 2743 fps | 96% |
| Norma MRP | <<locked>> | 80% | 36,912 psi | 57% | 2736 fps | 96.3% |
| Norma URP | <<locked>> | 80% | 46,006 psi | 71% | 2861 fps | 99.9% |
| Ramshot Grand | 82.8 gr | 86% | 41,321 psi | 64% | 2825 fps | 95.3% |
| Ramshot Hunter | <<locked>> | 80% | 45,107 psi | 69% | 2854 fps | 99.2% |
| Ramshot Magnum | <<locked>> | 86% | 37,130 psi | 57% | 2700 fps | 95.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,326 psi | 44% | 1818 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 47,195 psi | 73% | 2890 fps | 99.9% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 45,440 psi | 70% | 2907 fps | 99.8% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 34,606 psi | 53% | 2710 fps | 95.7% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 45,672 psi | 70% | 2933 fps | 95.5% |
| Rottweil R 903 | <<locked>> | 80% | 53,983 psi | 83% | 2943 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 43,236 psi | 67% | 2779 fps | 95.6% |
| Rottweil R 905 | <<locked>> | 80% | 38,580 psi | 59% | 2717 fps | 95.4% |
| Rottweil R 907 | <<locked>> | 80% | 49,559 psi | 76% | 2881 fps | 98.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 48,370 psi | 74% | 2854 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 80% | 46,731 psi | 72% | 2841 fps | 99% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 53,664 psi | 83% | 2822 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 47,485 psi | 73% | 2799 fps | 99% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 38,247 psi | 59% | 2713 fps | 95.3% |
| Somchem S355 | <<locked>> | 80% | 53,650 psi | 83% | 2936 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 44,396 psi | 68% | 2762 fps | 95.2% |
| Somchem S365 | <<locked>> | 80% | 43,062 psi | 66% | 2815 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 39,276 psi | 60% | 2703 fps | 96.6% |
| Vihtavuori N150 | <<locked>> | 80% | 51,401 psi | 79% | 2858 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 47,601 psi | 73% | 2858 fps | 100% |
| Vihtavuori N165 | <<locked>> | 82% | 36,347 psi | 56% | 2625 fps | 95.2% |
| Vihtavuori N550 | <<locked>> | 80% | 47,036 psi | 72% | 2858 fps | 99.9% |
| Vihtavuori N555 | <<locked>> | 80% | 37,898 psi | 58% | 2717 fps | 99.3% |
| Vihtavuori N560 | <<locked>> | 86% | 45,963 psi | 71% | 2920 fps | 95.9% |
| Vihtavuori N565 | <<locked>> | 90% | 43,163 psi | 66% | 2838 fps | 95.3% |
| Vihtavuori N568 | <<locked>> | 96% | 46,731 psi | 72% | 2943 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 46,891 psi | 72% | 2808 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 48,950 psi | 75% | 2927 fps | 99.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 30,182 psi | 46% | 2648 fps | 99.5% |
| Winchester Supreme 780 | <<locked>> | 82% | 38,580 psi | 59% | 2680 fps | 95.4% |
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 79 powders for .300 Rem. Ultra Mag. loaded with the .308 | 155gr | Frontier RSBT. Hodgdon Retumbo delivers the highest muzzle velocity at 3,199 fps; across all powders the maximum-charge window runs from 1,975 fps to 3,199 fps. ADI AR 2217 gives the best case fill at 100 %, and 79 of the 79 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 1:10.5 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, Ramshot Grand, Alliant Reloder-26 rank at the top here: for .300 Rem. Ultra Mag. with the .308 | 155gr | Frontier RSBT they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Alliant Reloder-33, IMR 7977 Enduron, Vihtavuori N170 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.