Load Specifications
Load data in caliber .300 RCM with .308 | 148gr | Hasler ARIETE bullet and 95 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, ReloadSwiss RS 52 and ReloadSwiss RS 60.
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>> | 90% | 57,725 psi | 90% | 2940 fps | 100% |
| Accurate 2460 | <<locked>> | 86% | 56,217 psi | 88% | 2966 fps | 100% |
| Accurate 2495 | <<locked>> | 94% | 54,955 psi | 86% | 2949 fps | 100% |
| Accurate 2520 | <<locked>> | 88% | 54,389 psi | 85% | 2976 fps | 100% |
| Accurate 4064 | <<locked>> | 96% | 54,824 psi | 86% | 2995 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 47,152 psi | 74% | 2940 fps | 97.4% |
| Accurate LT-30 | <<locked>> | 84% | 57,435 psi | 90% | 2890 fps | 100% |
| Accurate LT-32 | <<locked>> | 82% | 54,592 psi | 86% | 2871 fps | 100% |
| ADI AR 2206H | <<locked>> | 92% | 57,087 psi | 89% | 3041 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 96% | 54,650 psi | 86% | 2982 fps | 99% |
| ADI AR 2219 | <<locked>> | 82% | 54,868 psi | 86% | 2966 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 90% | 56,376 psi | 88% | 2995 fps | 99.9% |
| Alliant AR-Comp | <<locked>> | 90% | 56,217 psi | 88% | 2972 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 84% | 54,331 psi | 85% | 3051 fps | 99.7% |
| Alliant Power Pro 2000-MR | <<locked>> | 94% | 56,753 psi | 89% | 3156 fps | 99.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 98% | 57,363 psi | 90% | 3051 fps | 99.9% |
| Alliant Reloder-10x | <<locked>> | 86% | 57,696 psi | 90% | 2953 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 94% | 54,824 psi | 86% | 3025 fps | 99.2% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 47,007 psi | 74% | 2953 fps | 97.6% |
| Alliant Reloder-17ᴾ | <<locked>> | 100% | 54,708 psi | 86% | 3117 fps | 99.8% |
| Baschieri & Pellagri 106 | <<locked>> | 84% | 56,797 psi | 89% | 2884 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 92% | 56,927 psi | 89% | 3051 fps | 99% |
| Bofors RP3 | <<locked>> | 96% | 54,201 psi | 85% | 3015 fps | 99.8% |
| Hodgdon Benchmark | <<locked>> | 88% | 55,027 psi | 86% | 2930 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 90% | 55,332 psi | 87% | 3022 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 88% | 57,348 psi | 90% | 3123 fps | 99.4% |
| Hodgdon H322 | <<locked>> | 86% | 57,014 psi | 89% | 2995 fps | 100% |
| Hodgdon H335 | <<locked>> | 84% | 54,491 psi | 85% | 2969 fps | 100% |
| Hodgdon H380 | <<locked>> | 96% | 55,782 psi | 87% | 3025 fps | 98.4% |
| Hodgdon H4895 | <<locked>> | 92% | 57,667 psi | 90% | 3051 fps | 99.8% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 43,033 psi | 67% | 2828 fps | 98.1% |
| Hodgdon LEVERevolution | <<locked>> | 94% | 56,695 psi | 89% | 3084 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,650 psi | 54% | 1821 fps | 100% |
| Hodgdon VARGET | <<locked>> | 92% | 55,593 psi | 87% | 3002 fps | 99.7% |
| IMR 3031 | <<locked>> | 92% | 56,913 psi | 89% | 3038 fps | 100% |
| IMR 4064 | <<locked>> | 96% | 57,609 psi | 90% | 3018 fps | 99.4% |
| IMR 4166 Enduron | <<locked>> | 92% | 54,708 psi | 86% | 2940 fps | 96% |
| IMR 4198 | <<locked>> | 84% | 54,708 psi | 86% | 2867 fps | 100% |
| IMR 4451 Enduronᴾ | <<locked>> | 100% | 57,232 psi | 90% | 3009 fps | 96.5% |
| IMR 4831ᴾ | <<locked>> | 100% | 45,281 psi | 71% | 2887 fps | 97.1% |
| IMR 4895 | <<locked>> | 94% | 56,188 psi | 88% | 3061 fps | 99.6% |
| IMR 8208 XBR | <<locked>> | 90% | 56,376 psi | 88% | 2995 fps | 99.9% |
| Lovex D073.5 | <<locked>> | 86% | 56,333 psi | 88% | 2979 fps | 100% |
| Lovex D073.6 | <<locked>> | 92% | 56,144 psi | 88% | 3012 fps | 100% |
| Lovex S060 | <<locked>> | 92% | 57,217 psi | 90% | 2969 fps | 99.6% |
| Lovex S062 | <<locked>> | 96% | 56,797 psi | 89% | 3012 fps | 100% |
| Lovex S065ᴾ | <<locked>> | 100% | 52,344 psi | 82% | 2940 fps | 97% |
| Norma 200 | <<locked>> | 82% | 57,174 psi | 90% | 2920 fps | 100% |
| Norma 201 | <<locked>> | 92% | 55,550 psi | 87% | 2982 fps | 99.9% |
| Norma 202 | <<locked>> | 92% | 56,173 psi | 88% | 2989 fps | 100% |
| Norma 203B | <<locked>> | 96% | 57,174 psi | 90% | 3061 fps | 99.7% |
| Norma URPᴾ | <<locked>> | 100% | 47,268 psi | 74% | 2940 fps | 97.4% |
| Ramshot Big Game | <<locked>> | 94% | 54,317 psi | 85% | 3031 fps | 99.3% |
| Ramshot TAC | <<locked>> | 90% | 57,058 psi | 89% | 3009 fps | 98% |
| Ramshot Wild Boar | <<locked>> | 90% | 55,999 psi | 88% | 3025 fps | 99.5% |
| Ramshot X-Terminator | <<locked>> | 88% | 57,682 psi | 90% | 2995 fps | 99.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,940 psi | 55% | 1860 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 86% | 56,028 psi | 88% | 2979 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 96% | 56,608 psi | 89% | 3009 fps | 97.1% |
| ReloadSwiss RS 52 | <<locked>> | 92% | 54,592 psi | 86% | 3087 fps | 99.1% |
| ReloadSwiss RS 60 | <<locked>> | 98% | 54,476 psi | 85% | 3127 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 47,166 psi | 74% | 2963 fps | 97.2% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 48,167 psi | 75% | 2982 fps | 96.6% |
| Rottweil R 901 | <<locked>> | 90% | 56,304 psi | 88% | 2966 fps | 100% |
| Rottweil R 902 | <<locked>> | 94% | 55,724 psi | 87% | 2976 fps | 99.9% |
| Rottweil R 903ᴾ | <<locked>> | 100% | 57,551 psi | 90% | 3054 fps | 99.9% |
| Shooters World Long Rifleᴾ | <<locked>> | 100% | 52,344 psi | 82% | 2940 fps | 97% |
| Shooters World Match Rifle | <<locked>> | 92% | 56,144 psi | 88% | 3012 fps | 100% |
| Shooters World Precision | <<locked>> | 96% | 56,797 psi | 89% | 3012 fps | 100% |
| Shooters World Tactical Rifle | <<locked>> | 84% | 55,753 psi | 87% | 2946 fps | 99.8% |
| SNPE Vectan BA6 1/2 | <<locked>> | 82% | 57,392 psi | 90% | 2628 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 82% | 54,984 psi | 86% | 2972 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 98% | 56,246 psi | 88% | 3071 fps | 99.5% |
| SNPE Vectan SP 3 | <<locked>> | 84% | 55,100 psi | 86% | 2927 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 90% | 54,998 psi | 86% | 2979 fps | 98.2% |
| SNPE Vectan SP 9 | <<locked>> | 92% | 55,317 psi | 87% | 3005 fps | 99.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 90% | 54,186 psi | 85% | 2877 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 98% | 57,725 psi | 90% | 2923 fps | 100% |
| Somchem S321 | <<locked>> | 86% | 53,998 psi | 85% | 2976 fps | 99.9% |
| Somchem S335 | <<locked>> | 92% | 56,797 psi | 89% | 2923 fps | 100% |
| Somchem S341 | <<locked>> | 90% | 54,621 psi | 86% | 2976 fps | 99.4% |
| Somchem S355 | <<locked>> | 98% | 54,549 psi | 85% | 3002 fps | 99.6% |
| Somchem S365ᴾ | <<locked>> | 100% | 41,901 psi | 66% | 2881 fps | 99.1% |
| Vihtavuori N130 | <<locked>> | 88% | 57,479 psi | 90% | 2897 fps | 100% |
| Vihtavuori N133 | <<locked>> | 90% | 54,215 psi | 85% | 2867 fps | 100% |
| Vihtavuori N135 | <<locked>> | 94% | 55,129 psi | 86% | 2946 fps | 100% |
| Vihtavuori N140 | <<locked>> | 94% | 56,507 psi | 89% | 2963 fps | 100% |
| Vihtavuori N150ᴾ | <<locked>> | 100% | 56,275 psi | 88% | 2982 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 49,763 psi | 78% | 2940 fps | 97.7% |
| Vihtavuori N530 | <<locked>> | 90% | 56,797 psi | 89% | 2992 fps | 100% |
| Vihtavuori N540 | <<locked>> | 94% | 54,853 psi | 86% | 2963 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 48,747 psi | 76% | 2940 fps | 97.4% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 51,111 psi | 80% | 2930 fps | 99.5% |
| Winchester 748 | <<locked>> | 90% | 56,434 psi | 88% | 3045 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 92% | 55,042 psi | 86% | 3015 fps | 99.7% |
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% | 42,076 psi | 66% | 2700 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 45,963 psi | 72% | 2808 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 34,084 psi | 53% | 2592 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 41,133 psi | 64% | 2753 fps | 99.5% |
| Accurate 4064 | <<locked>> | 80% | 32,271 psi | 51% | 2569 fps | 98.6% |
| Accurate 4350 | <<locked>> | 96% | 40,799 psi | 64% | 2818 fps | 95.8% |
| Accurate LT-30 | <<locked>> | 80% | 50,778 psi | 80% | 2792 fps | 100% |
| Accurate LT-32 | <<locked>> | 80% | 51,184 psi | 80% | 2815 fps | 100% |
| ADI AR 2206H | <<locked>> | 80% | 38,769 psi | 61% | 2700 fps | 96.5% |
| ADI AR 2208 | <<locked>> | 84% | 37,478 psi | 59% | 2651 fps | 95.3% |
| ADI AR 2219 | <<locked>> | 80% | 51,053 psi | 80% | 2910 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 80% | 40,872 psi | 64% | 2723 fps | 98.3% |
| Alliant AR-Comp | <<locked>> | 80% | 39,972 psi | 63% | 2726 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 47,442 psi | 74% | 2930 fps | 99% |
| Alliant Power Pro 2000-MR | 53.5 gr | 84% | 40,016 psi | 63% | 2828 fps | 95.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 31,981 psi | 50% | 2559 fps | 95.2% |
| Alliant Reloder-10x | <<locked>> | 80% | 47,848 psi | 75% | 2808 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 37,028 psi | 58% | 2680 fps | 95.4% |
| Alliant Reloder-16 | <<locked>> | 94% | 38,957 psi | 61% | 2776 fps | 95.1% |
| Alliant Reloder-17 | <<locked>> | 86% | 33,895 psi | 53% | 2680 fps | 95% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 49,864 psi | 78% | 2785 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 40,480 psi | 63% | 2756 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 31,169 psi | 49% | 2549 fps | 95% |
| Hodgdon Benchmark | <<locked>> | 80% | 42,757 psi | 67% | 2717 fps | 99% |
| Hodgdon BL-C2 | <<locked>> | 80% | 39,001 psi | 61% | 2730 fps | 98.4% |
| Hodgdon CFE223 | <<locked>> | 80% | 43,004 psi | 67% | 2871 fps | 97.2% |
| Hodgdon H322 | <<locked>> | 80% | 46,673 psi | 73% | 2838 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 47,659 psi | 75% | 2861 fps | 100% |
| Hodgdon H380 | <<locked>> | 88% | 42,540 psi | 67% | 2792 fps | 95.7% |
| Hodgdon H4895 | <<locked>> | 80% | 39,088 psi | 61% | 2713 fps | 97.2% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 33,286 psi | 52% | 2605 fps | 95% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 34,954 psi | 55% | 2667 fps | 96.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,512 psi | 40% | 1624 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 37,623 psi | 59% | 2664 fps | 96.7% |
| IMR 3031 | <<locked>> | 80% | 38,145 psi | 60% | 2723 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 36,782 psi | 58% | 2631 fps | 95.4% |
| IMR 4166 Enduron | <<locked>> | 90% | 51,358 psi | 80% | 2884 fps | 95.3% |
| IMR 4198 | <<locked>> | 80% | 48,385 psi | 76% | 2776 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 96% | 50,705 psi | 79% | 2900 fps | 95% |
| IMR 4831 | <<locked>> | 96% | 39,508 psi | 62% | 2769 fps | 95.5% |
| IMR 4895 | <<locked>> | 80% | 35,447 psi | 56% | 2657 fps | 95.6% |
| IMR 8208 XBR | <<locked>> | 80% | 40,872 psi | 64% | 2723 fps | 98.3% |
| Lovex D073.5 | <<locked>> | 80% | 45,774 psi | 72% | 2808 fps | 99.6% |
| Lovex D073.6 | <<locked>> | 80% | 36,985 psi | 58% | 2674 fps | 98.8% |
| Lovex S060 | <<locked>> | 80% | 39,508 psi | 62% | 2651 fps | 96.8% |
| Lovex S062 | <<locked>> | 80% | 34,171 psi | 54% | 2582 fps | 96.6% |
| Lovex S065 | <<locked>> | 96% | 46,267 psi | 73% | 2831 fps | 95.7% |
| Norma 200 | <<locked>> | 80% | 53,606 psi | 84% | 2871 fps | 100% |
| Norma 201 | <<locked>> | 80% | 37,724 psi | 59% | 2654 fps | 97.6% |
| Norma 202 | <<locked>> | 80% | 38,014 psi | 60% | 2674 fps | 99.4% |
| Norma 203B | <<locked>> | 82% | 36,376 psi | 57% | 2671 fps | 95.8% |
| Norma URP | <<locked>> | 96% | 41,336 psi | 65% | 2822 fps | 95.8% |
| Ramshot Big Game | <<locked>> | 82% | 35,955 psi | 56% | 2677 fps | 95.3% |
| Ramshot TAC | <<locked>> | 82% | 43,613 psi | 68% | 2769 fps | 95.1% |
| Ramshot Wild Boar | <<locked>> | 80% | 40,001 psi | 63% | 2736 fps | 96.9% |
| Ramshot X-Terminator | <<locked>> | 80% | 44,280 psi | 69% | 2769 fps | 97.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,672 psi | 40% | 1660 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 45,876 psi | 72% | 2815 fps | 99.8% |
| ReloadSwiss RS 50 | <<locked>> | 92% | 49,559 psi | 78% | 2890 fps | 95.6% |
| ReloadSwiss RS 52 | 50.7 gr | 82% | 38,435 psi | 60% | 2779 fps | 95.8% |
| ReloadSwiss RS 60 | 50.2 gr | 80% | 29,486 psi | 46% | 2559 fps | 95.6% |
| ReloadSwiss RS 62 | <<locked>> | 96% | 40,988 psi | 64% | 2838 fps | 95.4% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 45,121 psi | 71% | 2920 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 41,466 psi | 65% | 2713 fps | 99.6% |
| Rottweil R 902 | <<locked>> | 80% | 36,013 psi | 56% | 2608 fps | 97.1% |
| Rottweil R 903 | <<locked>> | 84% | 33,489 psi | 52% | 2602 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 96% | 46,267 psi | 73% | 2831 fps | 95.7% |
| Shooters World Match Rifle | <<locked>> | 80% | 36,985 psi | 58% | 2674 fps | 98.8% |
| Shooters World Precision | <<locked>> | 80% | 34,171 psi | 54% | 2582 fps | 96.6% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 48,602 psi | 76% | 2831 fps | 99.3% |
| SNPE Vectan BA6 1/2 | <<locked>> | 80% | 54,404 psi | 85% | 2592 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 80% | 51,648 psi | 81% | 2920 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 35,041 psi | 55% | 2661 fps | 95.1% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 48,704 psi | 76% | 2831 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 82% | 41,350 psi | 65% | 2733 fps | 95.1% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 37,246 psi | 58% | 2664 fps | 96.1% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 39,639 psi | 62% | 2631 fps | 99.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 32,518 psi | 51% | 2484 fps | 99.1% |
| Somchem S321 | <<locked>> | 80% | 43,801 psi | 69% | 2799 fps | 99% |
| Somchem S335 | <<locked>> | 80% | 38,943 psi | 61% | 2628 fps | 99.8% |
| Somchem S341 | <<locked>> | 80% | 38,421 psi | 60% | 2680 fps | 96.3% |
| Somchem S355 | <<locked>> | 84% | 34,737 psi | 54% | 2618 fps | 95.8% |
| Somchem S365 | <<locked>> | 90% | 30,255 psi | 47% | 2585 fps | 95.2% |
| Vihtavuori N130 | <<locked>> | 80% | 45,020 psi | 71% | 2713 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 39,842 psi | 62% | 2635 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 35,027 psi | 55% | 2605 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 36,027 psi | 56% | 2608 fps | 99.3% |
| Vihtavuori N150 | <<locked>> | 80% | 28,921 psi | 45% | 2448 fps | 95.1% |
| Vihtavuori N160 | <<locked>> | 94% | 40,930 psi | 64% | 2772 fps | 95.6% |
| Vihtavuori N530 | <<locked>> | 80% | 40,756 psi | 64% | 2713 fps | 98.3% |
| Vihtavuori N540 | <<locked>> | 80% | 34,505 psi | 54% | 2589 fps | 98.7% |
| Vihtavuori N550 | <<locked>> | 94% | 40,001 psi | 63% | 2769 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 34,069 psi | 53% | 2582 fps | 95.4% |
| Winchester 748 | <<locked>> | 80% | 39,798 psi | 62% | 2753 fps | 98.8% |
| Winchester StaBALL Match | <<locked>> | 80% | 36,564 psi | 57% | 2667 fps | 96.5% |
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 111 powders for .300 RCM loaded with the .308 | 148gr | Hasler ARIETE. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,156 fps; across all powders the maximum-charge window runs from 1,821 fps to 3,156 fps. Accurate 4350 gives the best case fill at 100 %, and 111 of the 111 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 51–90 %, leaving at least 10 % headroom. The 148.0 gr projectile in 0.308" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Accurate 4350, Alliant Reloder-16, Alliant Reloder-17 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, ReloadSwiss RS 52, ReloadSwiss RS 60 rank at the top here: for .300 RCM with the .308 | 148gr | Hasler ARIETE they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Alliant Reloder-23, Alliant Reloder-26, Hodgdon H4350 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.