Load Specifications
Load data in caliber .300 H&H Mag. with .308 | 180gr | Sellier & Bellot XRG bullet and 97 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 70, Alliant Reloder-16 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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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 2495 | <<locked>> | 82% | 53,127 psi | 85% | 2667 fps | 100% |
| Accurate 2700 | <<locked>> | 84% | 54,302 psi | 87% | 2726 fps | 98.3% |
| Accurate 3100ᴾ | <<locked>> | 100% | 51,256 psi | 82% | 2762 fps | 99.1% |
| Accurate 4064 | <<locked>> | 84% | 53,330 psi | 86% | 2717 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 53,476 psi | 86% | 2815 fps | 100% |
| Accurate High Countryᴾ | <<locked>> | 100% | 55,695 psi | 89% | 2949 fps | 97.1% |
| ADI AR 2206H | <<locked>> | 82% | 55,738 psi | 89% | 2789 fps | 100% |
| ADI AR 2208 | <<locked>> | 86% | 53,490 psi | 86% | 2746 fps | 100% |
| ADI AR 2209 | <<locked>> | 98% | 54,418 psi | 87% | 2848 fps | 97.6% |
| Alliant Power Pro 2000-MR | <<locked>> | 84% | 55,985 psi | 90% | 2913 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 54,491 psi | 87% | 2848 fps | 97.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 54,230 psi | 87% | 2769 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 54,476 psi | 87% | 2789 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 94% | 54,215 psi | 87% | 2867 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 90% | 55,550 psi | 89% | 2897 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 53,722 psi | 86% | 2838 fps | 97.6% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 50,807 psi | 81% | 2838 fps | 97.2% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 47,979 psi | 77% | 2782 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 41,974 psi | 67% | 2697 fps | 98.3% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 54,969 psi | 88% | 2969 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 55,724 psi | 89% | 2808 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 46,572 psi | 75% | 2759 fps | 96.1% |
| Bofors RP3 | <<locked>> | 86% | 55,013 psi | 88% | 2785 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 50,807 psi | 81% | 2838 fps | 97.2% |
| Bofors RP7 | <<locked>> | 90% | 54,360 psi | 87% | 2762 fps | 98.5% |
| Hodgdon H380 | <<locked>> | 86% | 55,332 psi | 89% | 2799 fps | 99.9% |
| Hodgdon H414 | <<locked>> | 92% | 55,622 psi | 89% | 2861 fps | 99.1% |
| Hodgdon H4350 | <<locked>> | 90% | 55,680 psi | 89% | 2822 fps | 98.2% |
| Hodgdon H4831ᴾ | <<locked>> | 100% | 55,854 psi | 90% | 2841 fps | 96% |
| Hodgdon H4895 | <<locked>> | 82% | 56,333 psi | 90% | 2799 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 54,462 psi | 87% | 2795 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 56,420 psi | 90% | 2835 fps | 100% |
| Hodgdon Superformance | <<locked>> | 92% | 55,825 psi | 90% | 2900 fps | 99% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,230 psi | 58% | 1719 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 53,853 psi | 86% | 2749 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 56,333 psi | 90% | 2779 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 55,564 psi | 89% | 2759 fps | 99% |
| IMR 4350 | <<locked>> | 94% | 54,998 psi | 88% | 2795 fps | 98.6% |
| IMR 4451 Enduron | <<locked>> | 90% | 55,956 psi | 90% | 2792 fps | 99% |
| IMR 4831 | <<locked>> | 94% | 54,085 psi | 87% | 2808 fps | 100% |
| IMR 4895 | <<locked>> | 84% | 55,883 psi | 90% | 2818 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 54,070 psi | 87% | 2779 fps | 95.8% |
| Lovex D073.6 | <<locked>> | 82% | 56,144 psi | 90% | 2766 fps | 100% |
| Lovex S060 | <<locked>> | 82% | 54,679 psi | 88% | 2717 fps | 100% |
| Lovex S062 | <<locked>> | 86% | 56,434 psi | 90% | 2769 fps | 100% |
| Lovex S065 | <<locked>> | 92% | 56,115 psi | 90% | 2792 fps | 99.7% |
| Lovex S070 | <<locked>> | 92% | 53,766 psi | 86% | 2776 fps | 99% |
| Lovex S071ᴾ | <<locked>> | 100% | 42,656 psi | 68% | 2615 fps | 97.7% |
| Norma 201 | <<locked>> | 82% | 54,578 psi | 88% | 2733 fps | 100% |
| Norma 202 | <<locked>> | 82% | 55,172 psi | 88% | 2733 fps | 100% |
| Norma 203B | <<locked>> | 84% | 53,766 psi | 86% | 2776 fps | 100% |
| Norma 204 | <<locked>> | 94% | 55,883 psi | 90% | 2848 fps | 97.8% |
| Norma MRPᴾ | <<locked>> | 100% | 53,780 psi | 86% | 2920 fps | 98.9% |
| Norma URP | <<locked>> | 94% | 55,854 psi | 90% | 2851 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 54,230 psi | 87% | 2799 fps | 100% |
| Ramshot Hunter | <<locked>> | 94% | 54,665 psi | 88% | 2851 fps | 99.5% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 44,251 psi | 71% | 2697 fps | 96.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,999 psi | 59% | 1762 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 55,361 psi | 89% | 2782 fps | 99.3% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 55,143 psi | 88% | 2854 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 54,955 psi | 88% | 2887 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 53,214 psi | 85% | 2835 fps | 99.9% |
| ReloadSwiss RS 70 | <<locked>> | 94% | 55,390 psi | 89% | 2913 fps | 100% |
| Rottweil R 902 | <<locked>> | 84% | 55,187 psi | 88% | 2736 fps | 100% |
| Rottweil R 903 | <<locked>> | 88% | 54,839 psi | 88% | 2779 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 52,837 psi | 85% | 2766 fps | 96.2% |
| Rottweil R 905ᴾ | <<locked>> | 100% | 56,376 psi | 90% | 2877 fps | 98.2% |
| Rottweil R 907 | <<locked>> | 90% | 54,360 psi | 87% | 2762 fps | 98.5% |
| Shooters World Long Rifle | <<locked>> | 92% | 56,115 psi | 90% | 2792 fps | 99.7% |
| Shooters World Match Rifle | <<locked>> | 82% | 56,144 psi | 90% | 2766 fps | 100% |
| Shooters World Precision | <<locked>> | 86% | 56,434 psi | 90% | 2769 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 53,766 psi | 86% | 2776 fps | 99% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 56,289 psi | 90% | 2835 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 54,099 psi | 87% | 2759 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 55,506 psi | 89% | 2667 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 56,072 psi | 90% | 2667 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 92% | 55,985 psi | 90% | 2746 fps | 99% |
| SNPE Vectan Tubal 8000ᴾ | <<locked>> | 100% | 55,869 psi | 90% | 2874 fps | 98.1% |
| Somchem S335 | <<locked>> | 82% | 55,129 psi | 88% | 2667 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 54,969 psi | 88% | 2776 fps | 100% |
| Somchem S365 | <<locked>> | 96% | 54,824 psi | 88% | 2854 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 53,548 psi | 86% | 2802 fps | 98.4% |
| Vihtavuori N133 | <<locked>> | 82% | 55,941 psi | 90% | 2651 fps | 100% |
| Vihtavuori N135 | <<locked>> | 84% | 55,564 psi | 89% | 2697 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 55,608 psi | 89% | 2710 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 56,304 psi | 90% | 2753 fps | 100% |
| Vihtavuori N160 | <<locked>> | 92% | 54,418 psi | 87% | 2795 fps | 99.9% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 49,472 psi | 79% | 2723 fps | 97.3% |
| Vihtavuori N540 | <<locked>> | 84% | 53,867 psi | 86% | 2707 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 53,693 psi | 86% | 2802 fps | 99.9% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 53,621 psi | 86% | 2854 fps | 100% |
| Vihtavuori N560ᴾ | <<locked>> | 100% | 54,302 psi | 87% | 2907 fps | 96% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 54,085 psi | 87% | 2766 fps | 100% |
| Winchester 760 | <<locked>> | 92% | 55,898 psi | 90% | 2867 fps | 99.2% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 43,294 psi | 69% | 2828 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 82% | 54,099 psi | 87% | 2766 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 53,650 psi | 86% | 2795 fps | 97.4% |
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 2495 | <<locked>> | 80% | 49,922 psi | 80% | 2621 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 47,572 psi | 76% | 2615 fps | 97% |
| Accurate 3100 | <<locked>> | 88% | 34,185 psi | 55% | 2438 fps | 95% |
| Accurate 4064 | <<locked>> | 80% | 47,239 psi | 76% | 2628 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 35,578 psi | 57% | 2484 fps | 97.4% |
| Accurate High Country | <<locked>> | 96% | 48,515 psi | 78% | 2831 fps | 95.5% |
| ADI AR 2206H | <<locked>> | 80% | 52,272 psi | 84% | 2736 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 44,643 psi | 72% | 2598 fps | 99.5% |
| ADI AR 2209 | <<locked>> | 92% | 45,005 psi | 72% | 2684 fps | 95.4% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 48,718 psi | 78% | 2799 fps | 99.9% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 44,918 psi | 72% | 2680 fps | 95.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 45,005 psi | 72% | 2621 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 47,877 psi | 77% | 2684 fps | 99.8% |
| Alliant Reloder-16 | 53 gr | 80% | 34,925 psi | 56% | 2490 fps | 97.4% |
| Alliant Reloder-17 | <<locked>> | 80% | 39,305 psi | 63% | 2615 fps | 99.6% |
| Alliant Reloder-19 | <<locked>> | 92% | 44,425 psi | 71% | 2674 fps | 95.4% |
| Alliant Reloder-22 | <<locked>> | 96% | 44,440 psi | 71% | 2720 fps | 95.6% |
| Alliant Reloder-23 | <<locked>> | 82% | 27,296 psi | 44% | 2306 fps | 95.7% |
| Alliant Reloder-25 | <<locked>> | 94% | 34,795 psi | 56% | 2526 fps | 95.7% |
| Alliant Reloder-26 | 61.5 gr | 84% | 31,140 psi | 50% | 2470 fps | 95% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 52,069 psi | 83% | 2756 fps | 99.9% |
| Bofors RP15 | <<locked>> | 98% | 43,830 psi | 70% | 2707 fps | 95.2% |
| Bofors RP3 | <<locked>> | 80% | 45,034 psi | 72% | 2628 fps | 100% |
| Bofors RP5 | <<locked>> | 96% | 44,440 psi | 71% | 2720 fps | 95.6% |
| Bofors RP7 | <<locked>> | 80% | 39,856 psi | 64% | 2500 fps | 95.2% |
| Hodgdon H380 | <<locked>> | 80% | 45,469 psi | 73% | 2638 fps | 99% |
| Hodgdon H414 | <<locked>> | 80% | 37,594 psi | 60% | 2530 fps | 95.1% |
| Hodgdon H4350 | <<locked>> | 82% | 43,207 psi | 69% | 2605 fps | 95.4% |
| Hodgdon H4831 | <<locked>> | 98% | 52,431 psi | 84% | 2789 fps | 95.2% |
| Hodgdon H4895 | <<locked>> | 80% | 52,852 psi | 85% | 2746 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 32,532 psi | 52% | 2395 fps | 98.1% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 49,530 psi | 79% | 2733 fps | 100% |
| Hodgdon Superformance | <<locked>> | 82% | 39,204 psi | 63% | 2592 fps | 95.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,050 psi | 43% | 1535 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 50,676 psi | 81% | 2700 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 46,949 psi | 75% | 2631 fps | 99.8% |
| IMR 4166 Enduron | <<locked>> | 80% | 49,168 psi | 79% | 2654 fps | 98.1% |
| IMR 4350 | <<locked>> | 84% | 40,495 psi | 65% | 2536 fps | 95.4% |
| IMR 4451 Enduron | <<locked>> | 80% | 41,292 psi | 66% | 2533 fps | 96.2% |
| IMR 4831 | <<locked>> | 80% | 34,360 psi | 55% | 2441 fps | 97.1% |
| IMR 4895 | <<locked>> | 80% | 49,052 psi | 79% | 2713 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 96% | 50,923 psi | 82% | 2726 fps | 95.1% |
| Lovex D073.6 | <<locked>> | 80% | 52,562 psi | 84% | 2713 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 51,532 psi | 83% | 2667 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 47,166 psi | 76% | 2628 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 38,943 psi | 62% | 2487 fps | 97% |
| Lovex S070 | <<locked>> | 80% | 37,202 psi | 60% | 2464 fps | 95.2% |
| Lovex S071 | <<locked>> | 94% | 35,201 psi | 56% | 2461 fps | 95.4% |
| Norma 201 | <<locked>> | 80% | 51,445 psi | 82% | 2687 fps | 100% |
| Norma 202 | <<locked>> | 80% | 51,924 psi | 83% | 2684 fps | 100% |
| Norma 203B | <<locked>> | 80% | 47,239 psi | 76% | 2671 fps | 99.9% |
| Norma 204 | <<locked>> | 88% | 45,527 psi | 73% | 2674 fps | 95.5% |
| Norma MRP | <<locked>> | 90% | 38,305 psi | 61% | 2618 fps | 95.1% |
| Norma URP | <<locked>> | 80% | 35,621 psi | 57% | 2480 fps | 97.3% |
| Ramshot Big Game | <<locked>> | 80% | 47,398 psi | 76% | 2694 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 82% | 36,709 psi | 59% | 2516 fps | 95.8% |
| Ramshot Magnum | <<locked>> | 98% | 41,263 psi | 66% | 2635 fps | 95.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,615 psi | 44% | 1575 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 45,527 psi | 73% | 2618 fps | 97.9% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 51,488 psi | 83% | 2799 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 41,756 psi | 67% | 2671 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 35,331 psi | 57% | 2500 fps | 97% |
| ReloadSwiss RS 70 | 58 gr | 80% | 34,490 psi | 55% | 2500 fps | 96% |
| Rottweil R 902 | <<locked>> | 80% | 48,950 psi | 78% | 2641 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 42,627 psi | 68% | 2582 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 94% | 49,705 psi | 80% | 2717 fps | 95.4% |
| Rottweil R 905 | <<locked>> | 92% | 43,337 psi | 69% | 2654 fps | 95.3% |
| Rottweil R 907 | <<locked>> | 80% | 39,856 psi | 64% | 2500 fps | 95.2% |
| Shooters World Long Rifle | <<locked>> | 80% | 38,943 psi | 62% | 2487 fps | 97% |
| Shooters World Match Rifle | <<locked>> | 80% | 52,562 psi | 84% | 2713 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 47,166 psi | 76% | 2628 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 37,202 psi | 60% | 2464 fps | 95.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 43,410 psi | 70% | 2628 fps | 99.7% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 50,763 psi | 81% | 2710 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 52,199 psi | 84% | 2621 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 44,034 psi | 71% | 2497 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 38,145 psi | 61% | 2431 fps | 95.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 42,917 psi | 69% | 2651 fps | 95.2% |
| Somchem S335 | <<locked>> | 80% | 52,011 psi | 83% | 2625 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 43,004 psi | 69% | 2579 fps | 99.8% |
| Somchem S365 | <<locked>> | 80% | 32,111 psi | 51% | 2441 fps | 99.1% |
| Somchem S385 | <<locked>> | 90% | 41,350 psi | 66% | 2585 fps | 95.7% |
| Vihtavuori N133 | <<locked>> | 80% | 52,678 psi | 84% | 2608 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 49,052 psi | 79% | 2608 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 49,284 psi | 79% | 2621 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 41,017 psi | 66% | 2513 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 36,782 psi | 59% | 2477 fps | 97.6% |
| Vihtavuori N165 | <<locked>> | 96% | 43,265 psi | 69% | 2612 fps | 95.7% |
| Vihtavuori N540 | <<locked>> | 80% | 47,456 psi | 76% | 2612 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 36,347 psi | 58% | 2480 fps | 97.2% |
| Vihtavuori N555 | <<locked>> | 80% | 27,978 psi | 45% | 2329 fps | 95% |
| Vihtavuori N560 | <<locked>> | 98% | 50,807 psi | 81% | 2848 fps | 95.2% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 36,129 psi | 58% | 2454 fps | 99.2% |
| Winchester 760 | <<locked>> | 80% | 37,594 psi | 60% | 2530 fps | 95.1% |
| Winchester StaBALL HD | <<locked>> | 84% | 25,686 psi | 41% | 2326 fps | 95.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 50,763 psi | 81% | 2717 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 43,598 psi | 70% | 2621 fps | 95% |
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 H&H Mag. loaded with the .308 | 180gr | Sellier & Bellot XRG. Alliant Reloder-26 delivers the highest muzzle velocity at 2,969 fps; across all powders the maximum-charge window runs from 1,719 fps to 2,969 fps. Accurate 3100 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 (430 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 180.0 gr projectile in 0.308" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Accurate 3100, Accurate High Country, Alliant Reloder-22 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. ReloadSwiss RS 70, Alliant Reloder-16, Alliant Reloder-26 rank at the top here: for .300 H&H Mag. with the .308 | 180gr | Sellier & Bellot XRG 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.