Load Specifications
Load data in caliber .300 RCM with .308 | 180gr | MAKER Expanding Subsonic bullet and 99 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Power Pro 2000-MR, Hodgdon Superformance and Alliant Reloder-17.
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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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% | 56,594 psi | 89% | 2644 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 55,390 psi | 87% | 2671 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 57,159 psi | 90% | 2736 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 54,505 psi | 85% | 2680 fps | 97.5% |
| Accurate 3100ᴾ | <<locked>> | 100% | 42,293 psi | 66% | 2582 fps | 96.8% |
| Accurate 4064 | <<locked>> | 90% | 55,492 psi | 87% | 2720 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 55,143 psi | 86% | 2805 fps | 99.8% |
| ADI AR 2206H | <<locked>> | 86% | 55,753 psi | 87% | 2753 fps | 100% |
| ADI AR 2208 | <<locked>> | 92% | 56,536 psi | 89% | 2749 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 84% | 54,679 psi | 86% | 2703 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 55,550 psi | 87% | 2671 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 55,405 psi | 87% | 2871 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 56,942 psi | 89% | 2772 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 90% | 57,508 psi | 90% | 2795 fps | 100% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 56,376 psi | 88% | 2861 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 94% | 53,998 psi | 85% | 2844 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 40,335 psi | 63% | 2612 fps | 99.4% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 45,194 psi | 71% | 2769 fps | 98.8% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 55,521 psi | 87% | 2766 fps | 99.9% |
| Bofors RP3 | <<locked>> | 92% | 57,696 psi | 90% | 2789 fps | 100% |
| Bofors RP7 | <<locked>> | 96% | 57,464 psi | 90% | 2762 fps | 98.2% |
| Hodgdon Benchmark | <<locked>> | 84% | 56,217 psi | 88% | 2680 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 57,682 psi | 90% | 2779 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 56,057 psi | 88% | 2828 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 54,752 psi | 86% | 2753 fps | 99.6% |
| Hodgdon H414 | <<locked>> | 96% | 54,288 psi | 85% | 2802 fps | 98.3% |
| Hodgdon H4350 | <<locked>> | 94% | 55,158 psi | 86% | 2769 fps | 97.2% |
| Hodgdon H4895 | <<locked>> | 86% | 56,304 psi | 88% | 2762 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 52,678 psi | 83% | 2740 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 55,738 psi | 87% | 2792 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 54,984 psi | 86% | 2841 fps | 98.1% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,592 psi | 56% | 1660 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 57,479 psi | 90% | 2762 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 56,275 psi | 88% | 2736 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 56,231 psi | 88% | 2733 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 88% | 56,101 psi | 88% | 2717 fps | 98.4% |
| IMR 4350ᴾ | <<locked>> | 100% | 57,682 psi | 90% | 2789 fps | 98.2% |
| IMR 4451 Enduron | <<locked>> | 94% | 55,912 psi | 88% | 2743 fps | 98.3% |
| IMR 4831ᴾ | <<locked>> | 100% | 55,550 psi | 87% | 2795 fps | 99.9% |
| IMR 4895 | <<locked>> | 88% | 55,390 psi | 87% | 2776 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 54,679 psi | 86% | 2703 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 55,463 psi | 87% | 2723 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 55,187 psi | 86% | 2680 fps | 100% |
| Lovex S062 | <<locked>> | 90% | 56,057 psi | 88% | 2730 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 55,274 psi | 87% | 2736 fps | 99.2% |
| Lovex S070 | <<locked>> | 98% | 56,173 psi | 88% | 2772 fps | 98.6% |
| Norma 201 | <<locked>> | 86% | 54,563 psi | 86% | 2697 fps | 100% |
| Norma 202 | <<locked>> | 86% | 54,868 psi | 86% | 2694 fps | 100% |
| Norma 203B | <<locked>> | 90% | 56,666 psi | 89% | 2782 fps | 100% |
| Norma 204 | <<locked>> | 98% | 54,665 psi | 86% | 2782 fps | 96.6% |
| Norma MRPᴾ | <<locked>> | 100% | 45,063 psi | 71% | 2726 fps | 96.3% |
| Norma URP | <<locked>> | 98% | 54,186 psi | 85% | 2792 fps | 99.8% |
| Ramshot Big Game | <<locked>> | 90% | 57,334 psi | 90% | 2808 fps | 100% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 56,608 psi | 89% | 2844 fps | 99.2% |
| Ramshot TAC | <<locked>> | 84% | 54,781 psi | 86% | 2723 fps | 99.3% |
| Ramshot Wild Boar | <<locked>> | 84% | 54,476 psi | 85% | 2740 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 55,448 psi | 87% | 2703 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,143 psi | 57% | 1699 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 57,406 psi | 90% | 2723 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 54,984 psi | 86% | 2733 fps | 98.7% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 54,186 psi | 85% | 2805 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 57,566 psi | 90% | 2894 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 54,781 psi | 86% | 2828 fps | 99.7% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 54,462 psi | 85% | 2858 fps | 99.6% |
| Rottweil R 901 | <<locked>> | 84% | 55,550 psi | 87% | 2677 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 54,998 psi | 86% | 2697 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 57,276 psi | 90% | 2779 fps | 100% |
| Rottweil R 907 | <<locked>> | 96% | 57,464 psi | 90% | 2762 fps | 98.2% |
| Shooters World Long Rifle | <<locked>> | 96% | 55,274 psi | 87% | 2736 fps | 99.2% |
| Shooters World Match Rifle | <<locked>> | 86% | 55,463 psi | 87% | 2723 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 56,057 psi | 88% | 2730 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 56,173 psi | 88% | 2772 fps | 98.6% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 55,347 psi | 87% | 2789 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 57,014 psi | 89% | 2753 fps | 99.7% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 57,624 psi | 90% | 2772 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 55,941 psi | 88% | 2635 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 56,231 psi | 88% | 2635 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 55,622 psi | 87% | 2694 fps | 98.3% |
| Somchem S321 | <<locked>> | 82% | 55,811 psi | 87% | 2733 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 55,405 psi | 87% | 2635 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 56,652 psi | 89% | 2743 fps | 100% |
| Somchem S355 | <<locked>> | 94% | 57,479 psi | 90% | 2776 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 52,141 psi | 82% | 2795 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 48,530 psi | 76% | 2684 fps | 96.6% |
| Vihtavuori N130 | <<locked>> | 82% | 55,550 psi | 87% | 2595 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 56,202 psi | 88% | 2618 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 54,752 psi | 86% | 2657 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 55,521 psi | 87% | 2677 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 55,405 psi | 87% | 2707 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 56,681 psi | 89% | 2789 fps | 99.8% |
| Vihtavuori N530 | <<locked>> | 84% | 55,027 psi | 86% | 2700 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 57,029 psi | 89% | 2720 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 55,724 psi | 87% | 2795 fps | 99.7% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 44,585 psi | 70% | 2687 fps | 99.3% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 57,014 psi | 89% | 2769 fps | 100% |
| Winchester 748 | <<locked>> | 84% | 55,071 psi | 86% | 2746 fps | 100% |
| Winchester 760 | <<locked>> | 96% | 54,592 psi | 86% | 2808 fps | 98.4% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 36,216 psi | 57% | 2625 fps | 99.4% |
| Winchester StaBALL Match | <<locked>> | 88% | 57,566 psi | 90% | 2779 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% | 50,053 psi | 78% | 2559 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 42,699 psi | 67% | 2490 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 49,966 psi | 78% | 2638 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 44,686 psi | 70% | 2516 fps | 95.3% |
| Accurate 3100 | <<locked>> | 96% | 36,825 psi | 58% | 2474 fps | 95.1% |
| Accurate 4064 | <<locked>> | 80% | 40,408 psi | 63% | 2490 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 31,894 psi | 50% | 2375 fps | 95.3% |
| ADI AR 2206H | <<locked>> | 80% | 46,180 psi | 72% | 2602 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 80% | 39,262 psi | 62% | 2457 fps | 98.1% |
| ADI Benchmark 8208 | <<locked>> | 80% | 48,225 psi | 76% | 2605 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 48,776 psi | 76% | 2582 fps | 100% |
| Alliant Power Pro 2000-MR | 50.9 gr | 80% | 42,047 psi | 66% | 2638 fps | 98.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 39,015 psi | 61% | 2480 fps | 99.2% |
| Alliant Reloder-15 | <<locked>> | 80% | 41,887 psi | 66% | 2543 fps | 98.8% |
| Alliant Reloder-16 | <<locked>> | 82% | 32,242 psi | 51% | 2388 fps | 95.4% |
| Alliant Reloder-17 | 50.1 gr | 80% | 33,634 psi | 53% | 2454 fps | 97.8% |
| Alliant Reloder-23 | <<locked>> | 88% | 27,920 psi | 44% | 2300 fps | 95% |
| Alliant Reloder-26 | <<locked>> | 92% | 34,229 psi | 54% | 2526 fps | 95.4% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 45,353 psi | 71% | 2605 fps | 98.9% |
| Bofors RP3 | <<locked>> | 80% | 38,696 psi | 61% | 2484 fps | 99.3% |
| Bofors RP7 | <<locked>> | 88% | 44,831 psi | 70% | 2559 fps | 95.6% |
| Hodgdon Benchmark | <<locked>> | 80% | 49,995 psi | 78% | 2592 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 47,195 psi | 74% | 2628 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 80% | 52,243 psi | 82% | 2772 fps | 99.9% |
| Hodgdon H380 | <<locked>> | 80% | 39,421 psi | 62% | 2487 fps | 97.2% |
| Hodgdon H414 | <<locked>> | 88% | 41,698 psi | 65% | 2585 fps | 95.6% |
| Hodgdon H4350 | <<locked>> | 88% | 45,440 psi | 71% | 2608 fps | 95% |
| Hodgdon H4895 | <<locked>> | 80% | 46,630 psi | 73% | 2612 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 27,760 psi | 44% | 2241 fps | 95.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 42,641 psi | 67% | 2585 fps | 99.7% |
| Hodgdon Superformance | 59.6 gr | 90% | 44,353 psi | 70% | 2661 fps | 95.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,585 psi | 42% | 1483 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 44,585 psi | 70% | 2562 fps | 99.7% |
| IMR 3031 | <<locked>> | 80% | 46,543 psi | 73% | 2602 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 41,249 psi | 65% | 2490 fps | 98.7% |
| IMR 4166 Enduron | <<locked>> | 80% | 43,743 psi | 69% | 2513 fps | 96% |
| IMR 4350 | <<locked>> | 90% | 42,351 psi | 66% | 2536 fps | 95% |
| IMR 4451 Enduron | <<locked>> | 84% | 41,234 psi | 65% | 2490 fps | 95.1% |
| IMR 4831 | <<locked>> | 82% | 31,067 psi | 49% | 2339 fps | 95% |
| IMR 4895 | <<locked>> | 80% | 42,902 psi | 67% | 2572 fps | 99.3% |
| IMR 8208 XBR | <<locked>> | 80% | 48,225 psi | 76% | 2605 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 45,382 psi | 71% | 2579 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 46,035 psi | 72% | 2536 fps | 99.6% |
| Lovex S062 | <<locked>> | 80% | 41,220 psi | 65% | 2493 fps | 99.7% |
| Lovex S065 | <<locked>> | 82% | 36,013 psi | 56% | 2388 fps | 95.1% |
| Lovex S070 | <<locked>> | 88% | 41,234 psi | 65% | 2516 fps | 95.6% |
| Norma 201 | <<locked>> | 80% | 45,107 psi | 71% | 2552 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 45,556 psi | 71% | 2556 fps | 100% |
| Norma 203B | <<locked>> | 80% | 41,234 psi | 65% | 2530 fps | 99% |
| Norma 204 | <<locked>> | 94% | 47,979 psi | 75% | 2674 fps | 95% |
| Norma MRP | <<locked>> | 98% | 42,235 psi | 66% | 2671 fps | 95.4% |
| Norma URP | <<locked>> | 82% | 32,387 psi | 51% | 2382 fps | 95.3% |
| Ramshot Big Game | <<locked>> | 80% | 40,799 psi | 64% | 2543 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 88% | 38,305 psi | 60% | 2523 fps | 95.4% |
| Ramshot TAC | <<locked>> | 80% | 48,037 psi | 75% | 2615 fps | 98.4% |
| Ramshot Wild Boar | <<locked>> | 80% | 47,834 psi | 75% | 2635 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 80% | 51,880 psi | 81% | 2651 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,919 psi | 42% | 1519 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 53,925 psi | 85% | 2677 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 39,813 psi | 62% | 2470 fps | 95.6% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 44,150 psi | 69% | 2641 fps | 99.1% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 35,810 psi | 56% | 2516 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 33,910 psi | 53% | 2448 fps | 95.6% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 36,187 psi | 57% | 2503 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 49,269 psi | 77% | 2585 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 43,105 psi | 68% | 2510 fps | 99.8% |
| Rottweil R 903 | <<locked>> | 80% | 36,550 psi | 57% | 2434 fps | 98.7% |
| Rottweil R 907 | <<locked>> | 88% | 44,831 psi | 70% | 2559 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 82% | 36,013 psi | 56% | 2388 fps | 95.1% |
| Shooters World Match Rifle | <<locked>> | 80% | 45,382 psi | 71% | 2579 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 41,220 psi | 65% | 2493 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 88% | 41,234 psi | 65% | 2516 fps | 95.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 37,260 psi | 58% | 2477 fps | 98.2% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 46,615 psi | 73% | 2592 fps | 98.6% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 44,512 psi | 70% | 2569 fps | 99.4% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 46,528 psi | 73% | 2500 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 38,798 psi | 61% | 2379 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 40,176 psi | 63% | 2438 fps | 95% |
| Somchem S321 | <<locked>> | 80% | 52,185 psi | 82% | 2680 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 45,977 psi | 72% | 2500 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 46,151 psi | 72% | 2585 fps | 99.6% |
| Somchem S355 | <<locked>> | 80% | 37,144 psi | 58% | 2434 fps | 98.6% |
| Somchem S365 | <<locked>> | 80% | 27,050 psi | 42% | 2277 fps | 96.6% |
| Somchem S385 | <<locked>> | 96% | 42,627 psi | 67% | 2579 fps | 95% |
| Vihtavuori N130 | <<locked>> | 80% | 52,373 psi | 82% | 2552 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 46,876 psi | 73% | 2493 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 42,685 psi | 67% | 2487 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 43,236 psi | 68% | 2497 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 35,476 psi | 56% | 2375 fps | 99.2% |
| Vihtavuori N160 | <<locked>> | 82% | 33,721 psi | 53% | 2382 fps | 95.7% |
| Vihtavuori N530 | <<locked>> | 80% | 48,356 psi | 76% | 2602 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 41,524 psi | 65% | 2487 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 33,054 psi | 52% | 2379 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 88% | 29,950 psi | 47% | 2372 fps | 95.2% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 31,299 psi | 49% | 2306 fps | 97.1% |
| Winchester 748 | <<locked>> | 80% | 48,153 psi | 75% | 2644 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 41,930 psi | 66% | 2589 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 92% | 27,949 psi | 44% | 2372 fps | 95.5% |
| Winchester StaBALL Match | <<locked>> | 80% | 44,208 psi | 69% | 2575 fps | 99.7% |
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 99 powders for .300 RCM loaded with the .308 | 180gr | MAKER Expanding Subsonic. ReloadSwiss RS 60 delivers the highest muzzle velocity at 2,894 fps; across all powders the maximum-charge window runs from 1,660 fps to 2,894 fps. Accurate 3100 gives the best case fill at 100 %, and 99 of the 99 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 180.0 gr projectile in 0.308" calls for a 1:13.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-16, Alliant Reloder-23 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 Power Pro 2000-MR, Hodgdon Superformance, Alliant Reloder-17 rank at the top here: for .300 RCM with the .308 | 180gr | MAKER Expanding Subsonic 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.