Load Specifications
Load data in caliber .300 RCM with .308 | 165gr | Barnes X BT bullet and 97 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-17, ReloadSwiss RS 60 and Alliant Power Pro 2000-MR.
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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 84% | 56,391 psi | 88% | 2740 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 56,086 psi | 88% | 2772 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 56,507 psi | 89% | 2825 fps | 100% |
| Accurate 2700 | <<locked>> | 90% | 57,188 psi | 90% | 2802 fps | 96.8% |
| Accurate 4064 | <<locked>> | 90% | 55,666 psi | 87% | 2815 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 54,288 psi | 85% | 2887 fps | 99.3% |
| ADI AR 2206H | <<locked>> | 86% | 54,926 psi | 86% | 2831 fps | 99.8% |
| ADI AR 2208 | <<locked>> | 92% | 55,709 psi | 87% | 2831 fps | 99.7% |
| ADI Benchmark 8208 | <<locked>> | 86% | 57,101 psi | 89% | 2831 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 54,636 psi | 86% | 2762 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 54,041 psi | 85% | 2943 fps | 99.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 55,898 psi | 88% | 2858 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 90% | 56,478 psi | 89% | 2877 fps | 99.8% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 54,998 psi | 86% | 2933 fps | 99.6% |
| Alliant Reloder-17 | <<locked>> | 96% | 56,144 psi | 88% | 2972 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 40,176 psi | 63% | 2680 fps | 98.5% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 44,498 psi | 70% | 2831 fps | 97.5% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 54,389 psi | 85% | 2844 fps | 99.4% |
| Bofors RP3 | <<locked>> | 92% | 56,985 psi | 89% | 2877 fps | 100% |
| Bofors RP7 | <<locked>> | 96% | 56,652 psi | 89% | 2835 fps | 97% |
| Hodgdon Benchmark | <<locked>> | 84% | 55,593 psi | 87% | 2766 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 56,724 psi | 89% | 2864 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 54,650 psi | 86% | 2907 fps | 99.7% |
| Hodgdon H322 | <<locked>> | 82% | 57,740 psi | 90% | 2825 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 54,302 psi | 85% | 2835 fps | 99% |
| Hodgdon H414 | <<locked>> | 98% | 56,420 psi | 88% | 2923 fps | 97.7% |
| Hodgdon H4350 | <<locked>> | 96% | 57,334 psi | 90% | 2887 fps | 96.5% |
| Hodgdon H4895 | <<locked>> | 86% | 55,463 psi | 87% | 2844 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 51,430 psi | 81% | 2815 fps | 99.8% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 54,462 psi | 85% | 2874 fps | 100% |
| Hodgdon Superformance | <<locked>> | 98% | 57,348 psi | 90% | 2963 fps | 97.4% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,853 psi | 56% | 1726 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 56,275 psi | 88% | 2841 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 55,361 psi | 87% | 2828 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 55,187 psi | 86% | 2812 fps | 99.7% |
| IMR 4166 Enduron | <<locked>> | 88% | 55,158 psi | 86% | 2789 fps | 97.3% |
| IMR 4350ᴾ | <<locked>> | 100% | 56,362 psi | 88% | 2854 fps | 97% |
| IMR 4451 Enduron | <<locked>> | 94% | 54,824 psi | 86% | 2812 fps | 97.2% |
| IMR 4831ᴾ | <<locked>> | 100% | 54,476 psi | 85% | 2871 fps | 99.4% |
| IMR 4895 | <<locked>> | 88% | 54,476 psi | 85% | 2854 fps | 99.9% |
| IMR 8208 XBR | <<locked>> | 86% | 57,101 psi | 89% | 2831 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 55,143 psi | 86% | 2818 fps | 100% |
| Lovex S060 | <<locked>> | 88% | 57,638 psi | 90% | 2805 fps | 99.9% |
| Lovex S062 | <<locked>> | 90% | 55,637 psi | 87% | 2818 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 54,578 psi | 86% | 2812 fps | 98.4% |
| Lovex S070 | <<locked>> | 98% | 55,448 psi | 87% | 2844 fps | 97.6% |
| Norma 201 | <<locked>> | 88% | 57,624 psi | 90% | 2835 fps | 100% |
| Norma 202 | <<locked>> | 86% | 54,433 psi | 85% | 2785 fps | 100% |
| Norma 203B | <<locked>> | 90% | 55,724 psi | 87% | 2864 fps | 99.9% |
| Norma 204ᴾ | <<locked>> | 100% | 56,956 psi | 89% | 2904 fps | 95.7% |
| Norma URPᴾ | <<locked>> | 100% | 56,478 psi | 89% | 2920 fps | 99.5% |
| Ramshot Big Game | <<locked>> | 90% | 55,999 psi | 88% | 2887 fps | 99.9% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 54,969 psi | 86% | 2910 fps | 98.2% |
| Ramshot TAC | <<locked>> | 86% | 57,522 psi | 90% | 2851 fps | 98.9% |
| Ramshot Wild Boar | <<locked>> | 86% | 57,058 psi | 89% | 2871 fps | 99.9% |
| Ramshot X-Terminator | <<locked>> | 82% | 54,636 psi | 86% | 2782 fps | 99.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,448 psi | 57% | 1768 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 56,666 psi | 89% | 2812 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 54,215 psi | 85% | 2808 fps | 97.7% |
| ReloadSwiss RS 52 | <<locked>> | 88% | 56,739 psi | 89% | 2940 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 56,043 psi | 88% | 2976 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 57,000 psi | 89% | 2956 fps | 99.4% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 56,797 psi | 89% | 2982 fps | 99.3% |
| Rottweil R 901 | <<locked>> | 84% | 55,927 psi | 88% | 2776 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 54,665 psi | 86% | 2782 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 56,855 psi | 89% | 2867 fps | 100% |
| Rottweil R 907 | <<locked>> | 96% | 56,652 psi | 89% | 2835 fps | 97% |
| Shooters World Long Rifle | <<locked>> | 96% | 54,578 psi | 86% | 2812 fps | 98.4% |
| Shooters World Match Rifle | <<locked>> | 86% | 55,143 psi | 86% | 2818 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 55,637 psi | 87% | 2818 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 55,448 psi | 87% | 2844 fps | 97.6% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 54,404 psi | 85% | 2871 fps | 99.8% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 56,202 psi | 88% | 2831 fps | 99.1% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 56,565 psi | 89% | 2854 fps | 99.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 55,434 psi | 87% | 2723 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 55,216 psi | 87% | 2717 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 54,998 psi | 86% | 2766 fps | 97.2% |
| Somchem S321 | <<locked>> | 82% | 55,332 psi | 87% | 2822 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 54,882 psi | 86% | 2723 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 55,564 psi | 87% | 2822 fps | 99.8% |
| Somchem S355 | <<locked>> | 94% | 56,956 psi | 89% | 2864 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 50,966 psi | 80% | 2874 fps | 100% |
| Vihtavuori N130 | <<locked>> | 82% | 55,071 psi | 86% | 2684 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 55,477 psi | 87% | 2707 fps | 100% |
| Vihtavuori N135 | <<locked>> | 90% | 57,421 psi | 90% | 2792 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 54,592 psi | 86% | 2759 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 54,824 psi | 86% | 2792 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 55,347 psi | 87% | 2861 fps | 99.3% |
| Vihtavuori N530 | <<locked>> | 84% | 54,389 psi | 85% | 2785 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 56,463 psi | 88% | 2808 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 54,650 psi | 86% | 2871 fps | 99.1% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 43,947 psi | 69% | 2762 fps | 98.4% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 55,535 psi | 87% | 2838 fps | 100% |
| Winchester 748 | <<locked>> | 86% | 57,638 psi | 90% | 2881 fps | 100% |
| Winchester 760 | <<locked>> | 98% | 56,753 psi | 89% | 2930 fps | 97.8% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 36,303 psi | 57% | 2684 fps | 98.3% |
| Winchester StaBALL Match | <<locked>> | 88% | 56,391 psi | 88% | 2861 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 2015 | <<locked>> | 80% | 50,067 psi | 78% | 2651 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 44,208 psi | 69% | 2598 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 49,922 psi | 78% | 2730 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 50,372 psi | 79% | 2694 fps | 95.4% |
| Accurate 4064 | <<locked>> | 80% | 41,742 psi | 65% | 2592 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 34,621 psi | 54% | 2513 fps | 95% |
| ADI AR 2206H | <<locked>> | 80% | 46,021 psi | 72% | 2680 fps | 99% |
| ADI AR 2208 | <<locked>> | 80% | 39,247 psi | 62% | 2533 fps | 97.1% |
| ADI Benchmark 8208 | <<locked>> | 80% | 47,892 psi | 75% | 2687 fps | 99.8% |
| Alliant AR-Comp | <<locked>> | 80% | 48,240 psi | 76% | 2674 fps | 100% |
| Alliant Power Pro 2000-MR | 50.4 gr | 80% | 41,771 psi | 65% | 2710 fps | 97.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 39,146 psi | 61% | 2562 fps | 98.6% |
| Alliant Reloder-15 | <<locked>> | 80% | 41,959 psi | 66% | 2621 fps | 97.9% |
| Alliant Reloder-16 | <<locked>> | 86% | 36,593 psi | 57% | 2566 fps | 95.7% |
| Alliant Reloder-17 | 49.6 gr | 80% | 34,011 psi | 53% | 2530 fps | 96.6% |
| Alliant Reloder-23 | <<locked>> | 92% | 32,082 psi | 50% | 2480 fps | 95.6% |
| Alliant Reloder-26 | <<locked>> | 96% | 39,117 psi | 61% | 2713 fps | 95.8% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 44,976 psi | 70% | 2684 fps | 98.1% |
| Bofors RP3 | <<locked>> | 80% | 39,233 psi | 61% | 2572 fps | 98.7% |
| Bofors RP7 | <<locked>> | 90% | 47,514 psi | 74% | 2684 fps | 95% |
| Hodgdon Benchmark | <<locked>> | 80% | 49,603 psi | 78% | 2674 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 47,079 psi | 74% | 2713 fps | 99.9% |
| Hodgdon CFE223 | <<locked>> | 80% | 51,314 psi | 80% | 2854 fps | 99.4% |
| Hodgdon H322 | <<locked>> | 80% | 54,215 psi | 85% | 2776 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 39,726 psi | 62% | 2566 fps | 96.1% |
| Hodgdon H414 | <<locked>> | 92% | 46,862 psi | 73% | 2762 fps | 95.7% |
| Hodgdon H4350 | <<locked>> | 92% | 50,850 psi | 80% | 2782 fps | 95.1% |
| Hodgdon H4895 | <<locked>> | 80% | 46,485 psi | 73% | 2694 fps | 99.4% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 30,255 psi | 47% | 2372 fps | 95.1% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 42,279 psi | 66% | 2667 fps | 99.2% |
| Hodgdon Superformance | <<locked>> | 94% | 50,082 psi | 78% | 2841 fps | 95.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,818 psi | 42% | 1542 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 44,295 psi | 69% | 2641 fps | 99.1% |
| IMR 3031 | <<locked>> | 80% | 46,093 psi | 72% | 2690 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 41,220 psi | 65% | 2569 fps | 97.8% |
| IMR 4166 Enduron | <<locked>> | 82% | 46,151 psi | 72% | 2631 fps | 95.3% |
| IMR 4350 | <<locked>> | 94% | 47,297 psi | 74% | 2707 fps | 95% |
| IMR 4451 Enduron | <<locked>> | 88% | 46,122 psi | 72% | 2661 fps | 95.2% |
| IMR 4831 | <<locked>> | 86% | 35,578 psi | 56% | 2520 fps | 95.5% |
| IMR 4895 | <<locked>> | 80% | 42,902 psi | 67% | 2654 fps | 98.6% |
| IMR 8208 XBR | <<locked>> | 80% | 47,892 psi | 75% | 2687 fps | 99.8% |
| Lovex D073.6 | <<locked>> | 80% | 45,571 psi | 71% | 2667 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 45,803 psi | 72% | 2615 fps | 99% |
| Lovex S062 | <<locked>> | 80% | 41,568 psi | 65% | 2579 fps | 99.2% |
| Lovex S065 | <<locked>> | 86% | 40,959 psi | 64% | 2566 fps | 95.5% |
| Lovex S070 | <<locked>> | 90% | 43,888 psi | 69% | 2644 fps | 95% |
| Norma 201 | <<locked>> | 80% | 45,687 psi | 72% | 2641 fps | 99.7% |
| Norma 202 | <<locked>> | 80% | 45,513 psi | 71% | 2644 fps | 100% |
| Norma 203B | <<locked>> | 80% | 41,365 psi | 65% | 2612 fps | 98.3% |
| Norma 204 | <<locked>> | 98% | 53,519 psi | 84% | 2848 fps | 95% |
| Norma URP | <<locked>> | 86% | 36,825 psi | 58% | 2562 fps | 95.7% |
| Ramshot Big Game | <<locked>> | 80% | 40,611 psi | 64% | 2621 fps | 98% |
| Ramshot Hunter | <<locked>> | 92% | 43,192 psi | 68% | 2700 fps | 95.6% |
| Ramshot TAC | <<locked>> | 80% | 47,776 psi | 75% | 2690 fps | 97.4% |
| Ramshot Wild Boar | <<locked>> | 80% | 47,210 psi | 74% | 2713 fps | 99.2% |
| Ramshot X-Terminator | <<locked>> | 80% | 51,547 psi | 81% | 2733 fps | 99.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,238 psi | 43% | 1578 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 53,345 psi | 84% | 2762 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 42,424 psi | 66% | 2598 fps | 95% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 43,598 psi | 68% | 2720 fps | 98.3% |
| ReloadSwiss RS 60 | 49.6 gr | 80% | 35,998 psi | 56% | 2595 fps | 99.4% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 36,463 psi | 57% | 2579 fps | 95.2% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 38,653 psi | 61% | 2631 fps | 95% |
| Rottweil R 901 | <<locked>> | 80% | 49,879 psi | 78% | 2684 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 43,569 psi | 68% | 2595 fps | 99.4% |
| Rottweil R 903 | <<locked>> | 80% | 37,173 psi | 58% | 2520 fps | 98% |
| Rottweil R 907 | <<locked>> | 90% | 47,514 psi | 74% | 2684 fps | 95% |
| Shooters World Long Rifle | <<locked>> | 86% | 40,959 psi | 64% | 2566 fps | 95.5% |
| Shooters World Match Rifle | <<locked>> | 80% | 45,571 psi | 71% | 2667 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 41,568 psi | 65% | 2579 fps | 99.2% |
| Shooters World SW4350 | <<locked>> | 90% | 43,888 psi | 69% | 2644 fps | 95% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 37,304 psi | 58% | 2556 fps | 97.2% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 46,354 psi | 73% | 2671 fps | 97.6% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 44,309 psi | 69% | 2648 fps | 98.8% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 46,427 psi | 73% | 2585 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 38,870 psi | 61% | 2457 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 45,571 psi | 71% | 2612 fps | 95.2% |
| Somchem S321 | <<locked>> | 80% | 51,880 psi | 81% | 2769 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 46,383 psi | 73% | 2592 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 45,890 psi | 72% | 2667 fps | 99% |
| Somchem S355 | <<locked>> | 80% | 37,826 psi | 59% | 2523 fps | 97.9% |
| Somchem S365 | <<locked>> | 80% | 27,934 psi | 44% | 2362 fps | 95.6% |
| Vihtavuori N130 | <<locked>> | 80% | 52,054 psi | 82% | 2641 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 46,528 psi | 73% | 2579 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 42,772 psi | 67% | 2575 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 43,134 psi | 68% | 2582 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 35,868 psi | 56% | 2461 fps | 98.6% |
| Vihtavuori N160 | <<locked>> | 84% | 35,969 psi | 56% | 2507 fps | 95.2% |
| Vihtavuori N530 | <<locked>> | 80% | 48,037 psi | 75% | 2684 fps | 99.8% |
| Vihtavuori N540 | <<locked>> | 80% | 41,655 psi | 65% | 2572 fps | 100% |
| Vihtavuori N550 | <<locked>> | 86% | 37,768 psi | 59% | 2562 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 90% | 32,648 psi | 51% | 2510 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 31,807 psi | 50% | 2382 fps | 95.9% |
| Winchester 748 | <<locked>> | 80% | 47,645 psi | 75% | 2730 fps | 100% |
| Winchester 760 | <<locked>> | 92% | 47,166 psi | 74% | 2769 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 94% | 30,545 psi | 48% | 2500 fps | 95% |
| Winchester StaBALL Match | <<locked>> | 80% | 44,005 psi | 69% | 2657 fps | 99.2% |
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 97 powders for .300 RCM loaded with the .308 | 165gr | Barnes X BT. ReloadSwiss RS 70 delivers the highest muzzle velocity at 2,982 fps; across all powders the maximum-charge window runs from 1,726 fps to 2,982 fps. Alliant Reloder-16 gives the best case fill at 100 %, and 97 of the 97 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 56–90 %, 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. Alliant Reloder-16, Alliant Reloder-23, Alliant Reloder-26 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. Alliant Reloder-17, ReloadSwiss RS 60, Alliant Power Pro 2000-MR rank at the top here: for .300 RCM with the .308 | 165gr | Barnes X 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.