Load Specifications
Load data in caliber .375 H&H Mag. with .374 | 250gr | Rhino Penetrator 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 Hodgdon CFE223.
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>> | 90% | 54,563 psi | 87% | 2615 fps | 100% |
| Accurate 2200 | <<locked>> | 82% | 54,766 psi | 88% | 2700 fps | 98.7% |
| Accurate 2230 | <<locked>> | 82% | 55,796 psi | 89% | 2713 fps | 99.1% |
| Accurate 2460 | <<locked>> | 86% | 53,026 psi | 85% | 2638 fps | 100% |
| Accurate 2495 | <<locked>> | 96% | 54,998 psi | 88% | 2671 fps | 100% |
| Accurate 2520 | <<locked>> | 90% | 54,447 psi | 87% | 2694 fps | 100% |
| Accurate 4064 | <<locked>> | 98% | 54,476 psi | 87% | 2707 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 43,352 psi | 70% | 2598 fps | 96.2% |
| Accurate LT-30 | <<locked>> | 84% | 54,781 psi | 88% | 2566 fps | 100% |
| Accurate LT-32 | <<locked>> | 84% | 55,230 psi | 89% | 2589 fps | 100% |
| ADI AR 2206H | <<locked>> | 92% | 53,577 psi | 86% | 2694 fps | 99.2% |
| ADI AR 2207 | <<locked>> | 82% | 56,376 psi | 90% | 2585 fps | 100% |
| ADI AR 2208 | <<locked>> | 98% | 54,462 psi | 87% | 2687 fps | 98.8% |
| ADI AR 2219 | <<locked>> | 84% | 55,114 psi | 88% | 2680 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 92% | 56,405 psi | 90% | 2703 fps | 99.9% |
| Alliant AR-Comp | <<locked>> | 92% | 55,956 psi | 90% | 2687 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 86% | 54,447 psi | 87% | 2756 fps | 99.6% |
| Alliant Power Pro 2000-MR | <<locked>> | 96% | 56,420 psi | 90% | 2844 fps | 99% |
| Alliant Reloder- TS 15.5 | <<locked>> | 98% | 53,388 psi | 86% | 2707 fps | 99.6% |
| Alliant Reloder-10x | <<locked>> | 86% | 54,636 psi | 88% | 2625 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 96% | 54,346 psi | 87% | 2726 fps | 98.9% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 43,830 psi | 70% | 2605 fps | 96.3% |
| Alliant Reloder-17ᴾ | <<locked>> | 100% | 50,546 psi | 81% | 2756 fps | 99.2% |
| Baschieri & Pellagri 106 | <<locked>> | 84% | 53,809 psi | 86% | 2566 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 92% | 53,069 psi | 85% | 2703 fps | 98.3% |
| Bofors RP3 | <<locked>> | 98% | 53,751 psi | 86% | 2723 fps | 99.7% |
| Hodgdon Benchmark | <<locked>> | 90% | 55,332 psi | 89% | 2648 fps | 99.9% |
| Hodgdon BL-C2 | <<locked>> | 92% | 55,056 psi | 88% | 2730 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 88% | 53,185 psi | 85% | 2766 fps | 98.8% |
| Hodgdon H322 | <<locked>> | 86% | 53,650 psi | 86% | 2661 fps | 100% |
| Hodgdon H335 | <<locked>> | 86% | 54,781 psi | 88% | 2687 fps | 100% |
| Hodgdon H380 | <<locked>> | 98% | 55,593 psi | 89% | 2730 fps | 98.1% |
| Hodgdon H4895 | <<locked>> | 92% | 54,070 psi | 87% | 2707 fps | 99.5% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 40,132 psi | 64% | 2500 fps | 97.1% |
| Hodgdon LEVERevolution | <<locked>> | 96% | 55,999 psi | 90% | 2782 fps | 99.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,490 psi | 55% | 1604 fps | 100% |
| Hodgdon VARGET | <<locked>> | 94% | 55,477 psi | 89% | 2707 fps | 99.6% |
| IMR 3031 | <<locked>> | 92% | 52,982 psi | 85% | 2697 fps | 100% |
| IMR 4064 | <<locked>> | 96% | 54,056 psi | 87% | 2674 fps | 98.9% |
| IMR 4198 | <<locked>> | 86% | 55,042 psi | 88% | 2585 fps | 100% |
| IMR 4831ᴾ | <<locked>> | 100% | 41,655 psi | 67% | 2549 fps | 95.9% |
| IMR 4895 | <<locked>> | 96% | 55,680 psi | 89% | 2759 fps | 99.4% |
| IMR 8208 XBR | <<locked>> | 92% | 56,405 psi | 90% | 2703 fps | 99.9% |
| Lovex D073.5 | <<locked>> | 86% | 53,040 psi | 85% | 2648 fps | 99.9% |
| Lovex D073.6 | <<locked>> | 94% | 56,028 psi | 90% | 2723 fps | 100% |
| Lovex S060 | <<locked>> | 92% | 53,940 psi | 86% | 2628 fps | 99.2% |
| Lovex S062 | <<locked>> | 96% | 53,214 psi | 85% | 2671 fps | 99.7% |
| Lovex S065ᴾ | <<locked>> | 100% | 49,139 psi | 79% | 2605 fps | 96% |
| Norma 200 | <<locked>> | 82% | 54,549 psi | 87% | 2598 fps | 100% |
| Norma 201 | <<locked>> | 94% | 55,550 psi | 89% | 2690 fps | 99.9% |
| Norma 202 | <<locked>> | 94% | 55,956 psi | 90% | 2700 fps | 100% |
| Norma 203B | <<locked>> | 96% | 53,476 psi | 86% | 2717 fps | 99.2% |
| Norma URPᴾ | <<locked>> | 100% | 43,845 psi | 70% | 2598 fps | 96.2% |
| Ramshot Big Game | <<locked>> | 96% | 53,766 psi | 86% | 2736 fps | 99.1% |
| Ramshot TAC | <<locked>> | 90% | 53,563 psi | 86% | 2664 fps | 97.1% |
| Ramshot Wild Boar | <<locked>> | 92% | 56,028 psi | 90% | 2736 fps | 99.4% |
| Ramshot X-Terminator | <<locked>> | 88% | 54,418 psi | 87% | 2657 fps | 99.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,795 psi | 56% | 1644 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 88% | 56,275 psi | 90% | 2694 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 98% | 56,333 psi | 90% | 2710 fps | 96.6% |
| ReloadSwiss RS 52 | <<locked>> | 94% | 54,070 psi | 87% | 2789 fps | 98.9% |
| ReloadSwiss RS 60ᴾ | <<locked>> | 100% | 54,070 psi | 87% | 2822 fps | 100% |
| Rottweil R 901 | <<locked>> | 90% | 53,519 psi | 86% | 2638 fps | 100% |
| Rottweil R 902 | <<locked>> | 96% | 55,985 psi | 90% | 2687 fps | 99.9% |
| Rottweil R 903ᴾ | <<locked>> | 100% | 53,388 psi | 86% | 2707 fps | 99.5% |
| Shooters World Long Rifleᴾ | <<locked>> | 100% | 49,139 psi | 79% | 2605 fps | 96% |
| Shooters World Match Rifle | <<locked>> | 94% | 56,028 psi | 90% | 2723 fps | 100% |
| Shooters World Precision | <<locked>> | 96% | 53,214 psi | 85% | 2671 fps | 99.7% |
| Shooters World Tactical Rifle | <<locked>> | 86% | 56,420 psi | 90% | 2664 fps | 99.7% |
| SNPE Vectan BA6 1/2 | <<locked>> | 82% | 55,448 psi | 89% | 2336 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 84% | 55,405 psi | 89% | 2690 fps | 100% |
| SNPE Vectan SP 11ᴾ | <<locked>> | 100% | 55,434 psi | 89% | 2769 fps | 99.3% |
| SNPE Vectan SP 3 | <<locked>> | 86% | 55,521 psi | 89% | 2641 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 92% | 54,969 psi | 88% | 2690 fps | 97.8% |
| SNPE Vectan SP 9 | <<locked>> | 94% | 55,317 psi | 89% | 2717 fps | 99.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 92% | 54,694 psi | 88% | 2602 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 98% | 54,099 psi | 87% | 2595 fps | 100% |
| Somchem S321 | <<locked>> | 88% | 54,186 psi | 87% | 2690 fps | 99.9% |
| Somchem S335 | <<locked>> | 92% | 53,606 psi | 86% | 2598 fps | 100% |
| Somchem S341 | <<locked>> | 92% | 54,288 psi | 87% | 2687 fps | 99.1% |
| Somchem S355ᴾ | <<locked>> | 100% | 54,172 psi | 87% | 2710 fps | 99.5% |
| Somchem S365ᴾ | <<locked>> | 100% | 38,957 psi | 62% | 2546 fps | 98.2% |
| Vihtavuori N120 | <<locked>> | 82% | 56,202 psi | 90% | 2533 fps | 100% |
| Vihtavuori N130 | <<locked>> | 88% | 54,505 psi | 87% | 2572 fps | 100% |
| Vihtavuori N133 | <<locked>> | 92% | 54,505 psi | 87% | 2589 fps | 100% |
| Vihtavuori N135 | <<locked>> | 96% | 54,853 psi | 88% | 2661 fps | 100% |
| Vihtavuori N140 | <<locked>> | 94% | 53,055 psi | 85% | 2635 fps | 100% |
| Vihtavuori N150ᴾ | <<locked>> | 100% | 52,330 psi | 84% | 2648 fps | 99.8% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 46,224 psi | 74% | 2602 fps | 96.6% |
| Vihtavuori N530 | <<locked>> | 90% | 53,432 psi | 86% | 2654 fps | 99.7% |
| Vihtavuori N540 | <<locked>> | 96% | 54,737 psi | 88% | 2677 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 45,194 psi | 72% | 2605 fps | 96.3% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 47,601 psi | 76% | 2592 fps | 98.7% |
| Winchester 748 | <<locked>> | 92% | 55,927 psi | 90% | 2746 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 94% | 54,911 psi | 88% | 2723 fps | 99.6% |
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% | 40,132 psi | 64% | 2398 fps | 100% |
| Accurate 2200 | <<locked>> | 80% | 51,300 psi | 82% | 2648 fps | 98.2% |
| Accurate 2230 | <<locked>> | 80% | 51,996 psi | 83% | 2657 fps | 98.6% |
| Accurate 2460 | <<locked>> | 80% | 43,497 psi | 70% | 2490 fps | 99.8% |
| Accurate 2495 | <<locked>> | 80% | 32,634 psi | 52% | 2310 fps | 99.9% |
| Accurate 2520 | <<locked>> | 80% | 38,798 psi | 62% | 2444 fps | 99.1% |
| Accurate 4064 | <<locked>> | 80% | 30,864 psi | 49% | 2290 fps | 98.2% |
| Accurate 4350 | <<locked>> | 98% | 40,379 psi | 65% | 2546 fps | 95.4% |
| Accurate LT-30 | <<locked>> | 80% | 48,617 psi | 78% | 2480 fps | 100% |
| Accurate LT-32 | <<locked>> | 80% | 48,994 psi | 79% | 2500 fps | 99.9% |
| ADI AR 2206H | <<locked>> | 80% | 36,854 psi | 59% | 2395 fps | 95.7% |
| ADI AR 2207 | <<locked>> | 80% | 53,040 psi | 85% | 2543 fps | 100% |
| ADI AR 2208 | <<locked>> | 86% | 37,782 psi | 61% | 2398 fps | 95.1% |
| ADI AR 2219 | <<locked>> | 80% | 48,269 psi | 77% | 2582 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 80% | 38,870 psi | 62% | 2415 fps | 97.6% |
| Alliant AR-Comp | <<locked>> | 80% | 37,434 psi | 60% | 2421 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 44,788 psi | 72% | 2598 fps | 98.4% |
| Alliant Power Pro 2000-MR | 67.4 gr | 86% | 40,408 psi | 65% | 2559 fps | 95.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 32,198 psi | 52% | 2316 fps | 95.2% |
| Alliant Reloder-10x | <<locked>> | 80% | 45,455 psi | 73% | 2493 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 37,260 psi | 60% | 2425 fps | 95.2% |
| Alliant Reloder-16 | <<locked>> | 98% | 41,336 psi | 66% | 2556 fps | 95.5% |
| Alliant Reloder-17 | <<locked>> | 90% | 36,260 psi | 58% | 2477 fps | 95.7% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 47,311 psi | 76% | 2474 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 40,683 psi | 65% | 2493 fps | 95.6% |
| Bofors RP3 | <<locked>> | 82% | 31,546 psi | 51% | 2316 fps | 95.1% |
| Hodgdon Benchmark | <<locked>> | 80% | 41,017 psi | 66% | 2415 fps | 98.6% |
| Hodgdon BL-C2 | <<locked>> | 80% | 36,695 psi | 59% | 2421 fps | 97.7% |
| Hodgdon CFE223 | 64.2 gr | 80% | 40,364 psi | 65% | 2539 fps | 96.2% |
| Hodgdon H322 | <<locked>> | 80% | 44,150 psi | 71% | 2516 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 44,817 psi | 72% | 2539 fps | 99.9% |
| Hodgdon H380 | <<locked>> | 90% | 42,583 psi | 68% | 2520 fps | 95.3% |
| Hodgdon H4895 | <<locked>> | 80% | 37,115 psi | 60% | 2408 fps | 96.5% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 35,389 psi | 57% | 2402 fps | 95.5% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 33,083 psi | 53% | 2365 fps | 95.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,527 psi | 41% | 1430 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 35,766 psi | 57% | 2362 fps | 95.9% |
| IMR 3031 | <<locked>> | 80% | 35,839 psi | 57% | 2418 fps | 99.9% |
| IMR 4064 | <<locked>> | 84% | 37,289 psi | 60% | 2382 fps | 95.3% |
| IMR 4198 | <<locked>> | 80% | 46,311 psi | 74% | 2464 fps | 100% |
| IMR 4831 | <<locked>> | 98% | 39,015 psi | 63% | 2497 fps | 95% |
| IMR 4895 | <<locked>> | 82% | 35,737 psi | 57% | 2405 fps | 95.5% |
| IMR 8208 XBR | <<locked>> | 80% | 38,870 psi | 62% | 2415 fps | 97.6% |
| Lovex D073.5 | <<locked>> | 80% | 43,149 psi | 69% | 2490 fps | 99.2% |
| Lovex D073.6 | <<locked>> | 80% | 34,867 psi | 56% | 2375 fps | 98.2% |
| Lovex S060 | <<locked>> | 80% | 37,768 psi | 61% | 2349 fps | 96% |
| Lovex S062 | <<locked>> | 80% | 32,576 psi | 52% | 2293 fps | 95.8% |
| Lovex S065 | <<locked>> | 98% | 46,151 psi | 74% | 2556 fps | 95.2% |
| Norma 200 | <<locked>> | 80% | 51,343 psi | 82% | 2556 fps | 100% |
| Norma 201 | <<locked>> | 80% | 36,143 psi | 58% | 2359 fps | 97% |
| Norma 202 | <<locked>> | 80% | 36,100 psi | 58% | 2375 fps | 99% |
| Norma 203B | <<locked>> | 84% | 36,593 psi | 59% | 2415 fps | 95.7% |
| Norma URP | <<locked>> | 98% | 41,031 psi | 66% | 2546 fps | 95.4% |
| Ramshot Big Game | <<locked>> | 84% | 36,085 psi | 58% | 2421 fps | 95.1% |
| Ramshot TAC | <<locked>> | 86% | 46,992 psi | 75% | 2559 fps | 95.7% |
| Ramshot Wild Boar | <<locked>> | 80% | 37,652 psi | 60% | 2421 fps | 95.9% |
| Ramshot X-Terminator | <<locked>> | 80% | 41,989 psi | 67% | 2454 fps | 97% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,744 psi | 41% | 1467 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 43,511 psi | 70% | 2500 fps | 99.5% |
| ReloadSwiss RS 50 | <<locked>> | 94% | 49,371 psi | 79% | 2608 fps | 95.2% |
| ReloadSwiss RS 52 | 63.8 gr | 84% | 38,508 psi | 62% | 2513 fps | 95.6% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 29,994 psi | 48% | 2323 fps | 95.5% |
| Rottweil R 901 | <<locked>> | 80% | 39,784 psi | 64% | 2411 fps | 99.4% |
| Rottweil R 902 | <<locked>> | 80% | 34,330 psi | 55% | 2310 fps | 96.4% |
| Rottweil R 903 | <<locked>> | 86% | 33,808 psi | 54% | 2359 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 98% | 46,151 psi | 74% | 2556 fps | 95.2% |
| Shooters World Match Rifle | <<locked>> | 80% | 34,867 psi | 56% | 2375 fps | 98.2% |
| Shooters World Precision | <<locked>> | 80% | 32,576 psi | 52% | 2293 fps | 95.8% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 46,064 psi | 74% | 2510 fps | 98.7% |
| SNPE Vectan BA6 1/2 | <<locked>> | 80% | 52,692 psi | 84% | 2303 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 80% | 48,646 psi | 78% | 2592 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 37,536 psi | 60% | 2457 fps | 95.7% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 46,253 psi | 74% | 2513 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 41,901 psi | 67% | 2477 fps | 95% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 35,389 psi | 57% | 2362 fps | 95.1% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 37,913 psi | 61% | 2336 fps | 99.2% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 31,024 psi | 50% | 2205 fps | 98.6% |
| Somchem S321 | <<locked>> | 80% | 41,394 psi | 66% | 2484 fps | 98.5% |
| Somchem S335 | <<locked>> | 80% | 37,318 psi | 60% | 2336 fps | 99.6% |
| Somchem S341 | <<locked>> | 80% | 36,158 psi | 58% | 2372 fps | 95.3% |
| Somchem S355 | <<locked>> | 86% | 34,998 psi | 56% | 2369 fps | 95.7% |
| Somchem S365 | <<locked>> | 94% | 32,300 psi | 52% | 2388 fps | 95.9% |
| Vihtavuori N120 | <<locked>> | 80% | 52,866 psi | 85% | 2493 fps | 100% |
| Vihtavuori N130 | <<locked>> | 80% | 43,018 psi | 69% | 2411 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 37,971 psi | 61% | 2339 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 33,156 psi | 53% | 2313 fps | 99.9% |
| Vihtavuori N140 | <<locked>> | 80% | 34,026 psi | 55% | 2313 fps | 98.8% |
| Vihtavuori N150 | <<locked>> | 82% | 29,283 psi | 47% | 2218 fps | 95.1% |
| Vihtavuori N160 | <<locked>> | 96% | 40,611 psi | 65% | 2497 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 38,653 psi | 62% | 2408 fps | 97.7% |
| Vihtavuori N540 | <<locked>> | 80% | 32,692 psi | 52% | 2297 fps | 98.1% |
| Vihtavuori N550 | <<locked>> | 98% | 42,351 psi | 68% | 2552 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 36,521 psi | 59% | 2385 fps | 95.9% |
| Winchester 748 | <<locked>> | 80% | 37,391 psi | 60% | 2441 fps | 98.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 34,476 psi | 55% | 2362 fps | 95.6% |
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 95 powders for .375 H&H Mag. loaded with the .374 | 250gr | Rhino Penetrator. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 2,844 fps; across all powders the maximum-charge window runs from 1,604 fps to 2,844 fps. Accurate 4350 gives the best case fill at 100 %, and 95 of the 95 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (430 MPa), the top charges use 55–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.374" calls for a 1:6.0 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, Hodgdon CFE223 rank at the top here: for .375 H&H Mag. with the .374 | 250gr | Rhino Penetrator 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.