Load Specifications
Load data in caliber .375 H&H Mag. with .375 | 275gr | SUS-TAC HP 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 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% | 54,694 psi | 88% | 2461 fps | 100% |
| Accurate 2200 | <<locked>> | 82% | 55,042 psi | 88% | 2546 fps | 99.1% |
| Accurate 2230 | <<locked>> | 82% | 56,086 psi | 90% | 2562 fps | 99.4% |
| Accurate 2460 | <<locked>> | 86% | 53,171 psi | 85% | 2487 fps | 100% |
| Accurate 2495 | <<locked>> | 96% | 55,187 psi | 88% | 2516 fps | 100% |
| Accurate 2520 | <<locked>> | 90% | 54,447 psi | 87% | 2539 fps | 100% |
| Accurate 4064 | <<locked>> | 98% | 54,650 psi | 88% | 2552 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 43,250 psi | 69% | 2457 fps | 96.9% |
| Accurate LT-30 | <<locked>> | 84% | 54,984 psi | 88% | 2415 fps | 100% |
| Accurate LT-32 | <<locked>> | 84% | 55,376 psi | 89% | 2434 fps | 100% |
| ADI AR 2206H | <<locked>> | 92% | 53,766 psi | 86% | 2543 fps | 99.4% |
| ADI AR 2208 | <<locked>> | 98% | 54,491 psi | 87% | 2536 fps | 99.1% |
| ADI AR 2219 | <<locked>> | 84% | 55,347 psi | 89% | 2523 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 90% | 53,127 psi | 85% | 2503 fps | 99.9% |
| Alliant AR-Comp | <<locked>> | 92% | 55,956 psi | 90% | 2526 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 86% | 54,607 psi | 88% | 2598 fps | 99.8% |
| Alliant Power Pro 2000-MR | <<locked>> | 96% | 56,420 psi | 90% | 2687 fps | 99.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 98% | 53,316 psi | 85% | 2552 fps | 99.8% |
| Alliant Reloder-10x | <<locked>> | 86% | 54,926 psi | 88% | 2470 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 96% | 54,520 psi | 87% | 2575 fps | 99.3% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 43,918 psi | 70% | 2464 fps | 97% |
| Alliant Reloder-17ᴾ | <<locked>> | 100% | 50,430 psi | 81% | 2605 fps | 99.5% |
| Baschieri & Pellagri 106 | <<locked>> | 84% | 53,940 psi | 86% | 2415 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 92% | 53,127 psi | 85% | 2552 fps | 98.7% |
| Bofors RP3 | <<locked>> | 98% | 53,838 psi | 86% | 2569 fps | 99.9% |
| Hodgdon Benchmark | <<locked>> | 90% | 55,506 psi | 89% | 2493 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 92% | 54,940 psi | 88% | 2575 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 88% | 53,098 psi | 85% | 2612 fps | 99.2% |
| Hodgdon H322 | <<locked>> | 86% | 53,809 psi | 86% | 2507 fps | 100% |
| Hodgdon H335 | <<locked>> | 86% | 54,853 psi | 88% | 2533 fps | 100% |
| Hodgdon H380 | <<locked>> | 98% | 55,506 psi | 89% | 2579 fps | 98.5% |
| Hodgdon H4895 | <<locked>> | 92% | 54,186 psi | 87% | 2556 fps | 99.7% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 40,147 psi | 64% | 2365 fps | 97.7% |
| Hodgdon LEVERevolution | <<locked>> | 96% | 55,970 psi | 90% | 2625 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,432 psi | 55% | 1496 fps | 100% |
| Hodgdon VARGET | <<locked>> | 94% | 55,535 psi | 89% | 2556 fps | 99.8% |
| IMR 3031 | <<locked>> | 92% | 52,997 psi | 85% | 2539 fps | 100% |
| IMR 4064 | <<locked>> | 96% | 54,128 psi | 87% | 2523 fps | 99.2% |
| IMR 4166 Enduron | <<locked>> | 94% | 54,911 psi | 88% | 2500 fps | 96.2% |
| IMR 4198 | <<locked>> | 86% | 55,230 psi | 89% | 2431 fps | 100% |
| IMR 4451 Enduronᴾ | <<locked>> | 100% | 53,751 psi | 86% | 2513 fps | 95.9% |
| IMR 4831ᴾ | <<locked>> | 100% | 41,742 psi | 67% | 2411 fps | 96.5% |
| IMR 4895 | <<locked>> | 96% | 55,869 psi | 90% | 2605 fps | 99.7% |
| IMR 8208 XBR | <<locked>> | 90% | 53,127 psi | 85% | 2503 fps | 99.9% |
| Lovex D073.5 | <<locked>> | 86% | 53,026 psi | 85% | 2493 fps | 100% |
| Lovex D073.6 | <<locked>> | 94% | 56,072 psi | 90% | 2569 fps | 100% |
| Lovex S060 | <<locked>> | 92% | 54,027 psi | 87% | 2477 fps | 99.4% |
| Lovex S062 | <<locked>> | 96% | 53,301 psi | 85% | 2520 fps | 99.9% |
| Lovex S065ᴾ | <<locked>> | 100% | 49,081 psi | 79% | 2461 fps | 96.5% |
| Norma 200 | <<locked>> | 82% | 54,636 psi | 88% | 2441 fps | 100% |
| Norma 201 | <<locked>> | 94% | 55,637 psi | 89% | 2536 fps | 100% |
| Norma 202 | <<locked>> | 94% | 56,101 psi | 90% | 2546 fps | 100% |
| Norma 203B | <<locked>> | 96% | 53,621 psi | 86% | 2562 fps | 99.5% |
| Norma URPᴾ | <<locked>> | 100% | 43,888 psi | 70% | 2457 fps | 96.8% |
| Ramshot Big Game | <<locked>> | 96% | 53,722 psi | 86% | 2585 fps | 99.4% |
| Ramshot TAC | <<locked>> | 90% | 53,621 psi | 86% | 2516 fps | 97.6% |
| Ramshot Wild Boar | <<locked>> | 92% | 55,956 psi | 90% | 2579 fps | 99.6% |
| Ramshot X-Terminator | <<locked>> | 88% | 54,520 psi | 87% | 2507 fps | 99.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,838 psi | 56% | 1532 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 88% | 56,376 psi | 90% | 2536 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 98% | 56,231 psi | 90% | 2559 fps | 97.1% |
| ReloadSwiss RS 52 | <<locked>> | 94% | 54,114 psi | 87% | 2631 fps | 99.3% |
| ReloadSwiss RS 60ᴾ | <<locked>> | 100% | 53,867 psi | 86% | 2664 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 43,381 psi | 70% | 2477 fps | 96.4% |
| Rottweil R 901 | <<locked>> | 90% | 53,577 psi | 86% | 2484 fps | 100% |
| Rottweil R 902 | <<locked>> | 96% | 55,941 psi | 90% | 2533 fps | 100% |
| Rottweil R 903ᴾ | <<locked>> | 100% | 53,417 psi | 86% | 2556 fps | 99.7% |
| Shooters World Long Rifleᴾ | <<locked>> | 100% | 49,081 psi | 79% | 2461 fps | 96.5% |
| Shooters World Match Rifle | <<locked>> | 94% | 56,072 psi | 90% | 2569 fps | 100% |
| Shooters World Precision | <<locked>> | 96% | 53,301 psi | 85% | 2520 fps | 99.9% |
| Shooters World Tactical Rifle | <<locked>> | 84% | 52,750 psi | 85% | 2464 fps | 99.7% |
| SNPE Vectan BA6 1/2 | <<locked>> | 82% | 55,579 psi | 89% | 2188 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 84% | 55,506 psi | 89% | 2533 fps | 100% |
| SNPE Vectan SP 11ᴾ | <<locked>> | 100% | 55,317 psi | 89% | 2612 fps | 99.6% |
| SNPE Vectan SP 3 | <<locked>> | 86% | 55,811 psi | 89% | 2487 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 92% | 54,984 psi | 88% | 2539 fps | 98.3% |
| SNPE Vectan SP 9 | <<locked>> | 94% | 55,376 psi | 89% | 2562 fps | 99.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 92% | 54,694 psi | 88% | 2448 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 98% | 54,041 psi | 87% | 2444 fps | 100% |
| Somchem S321 | <<locked>> | 88% | 54,244 psi | 87% | 2539 fps | 100% |
| Somchem S335 | <<locked>> | 92% | 53,679 psi | 86% | 2448 fps | 100% |
| Somchem S341 | <<locked>> | 92% | 54,360 psi | 87% | 2533 fps | 99.4% |
| Somchem S355ᴾ | <<locked>> | 100% | 54,056 psi | 87% | 2556 fps | 99.7% |
| Somchem S365ᴾ | <<locked>> | 100% | 38,914 psi | 62% | 2408 fps | 98.7% |
| Vihtavuori N120 | <<locked>> | 82% | 56,347 psi | 90% | 2382 fps | 100% |
| Vihtavuori N130 | <<locked>> | 88% | 54,766 psi | 88% | 2421 fps | 100% |
| Vihtavuori N133 | <<locked>> | 92% | 54,534 psi | 87% | 2434 fps | 100% |
| Vihtavuori N135 | <<locked>> | 96% | 54,853 psi | 88% | 2503 fps | 100% |
| Vihtavuori N140 | <<locked>> | 94% | 53,055 psi | 85% | 2480 fps | 100% |
| Vihtavuori N150ᴾ | <<locked>> | 100% | 52,388 psi | 84% | 2497 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 46,224 psi | 74% | 2457 fps | 97.2% |
| Vihtavuori N530 | <<locked>> | 90% | 53,708 psi | 86% | 2507 fps | 99.9% |
| Vihtavuori N540 | <<locked>> | 96% | 54,621 psi | 88% | 2523 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 45,150 psi | 72% | 2461 fps | 96.9% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 47,543 psi | 76% | 2451 fps | 99.1% |
| Winchester 748 | <<locked>> | 92% | 56,173 psi | 90% | 2592 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 94% | 54,969 psi | 88% | 2572 fps | 99.8% |
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% | 40,263 psi | 65% | 2260 fps | 100% |
| Accurate 2200 | <<locked>> | 80% | 51,503 psi | 83% | 2497 fps | 98.7% |
| Accurate 2230 | <<locked>> | 80% | 52,228 psi | 84% | 2510 fps | 99% |
| Accurate 2460 | <<locked>> | 80% | 43,584 psi | 70% | 2349 fps | 99.9% |
| Accurate 2495 | <<locked>> | 80% | 32,735 psi | 52% | 2182 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 38,740 psi | 62% | 2303 fps | 99.4% |
| Accurate 4064 | <<locked>> | 80% | 30,995 psi | 50% | 2165 fps | 98.7% |
| Accurate 4350 | <<locked>> | 96% | 37,724 psi | 60% | 2359 fps | 95.3% |
| Accurate LT-30 | <<locked>> | 80% | 48,805 psi | 78% | 2333 fps | 100% |
| Accurate LT-32 | <<locked>> | 80% | 49,182 psi | 79% | 2352 fps | 100% |
| ADI AR 2206H | <<locked>> | 80% | 36,970 psi | 59% | 2264 fps | 96.4% |
| ADI AR 2208 | <<locked>> | 84% | 35,607 psi | 57% | 2218 fps | 95.1% |
| ADI AR 2219 | <<locked>> | 80% | 48,457 psi | 78% | 2434 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 80% | 38,928 psi | 62% | 2277 fps | 98.2% |
| Alliant AR-Comp | <<locked>> | 80% | 37,623 psi | 60% | 2280 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 44,875 psi | 72% | 2451 fps | 98.9% |
| Alliant Power Pro 2000-MR | 60.9 gr | 84% | 37,826 psi | 61% | 2362 fps | 95.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 30,371 psi | 49% | 2146 fps | 95.2% |
| Alliant Reloder-10x | <<locked>> | 80% | 45,672 psi | 73% | 2349 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 35,012 psi | 56% | 2244 fps | 95.2% |
| Alliant Reloder-16 | <<locked>> | 96% | 39,044 psi | 63% | 2369 fps | 95.5% |
| Alliant Reloder-17 | <<locked>> | 88% | 34,200 psi | 55% | 2297 fps | 95.6% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 47,384 psi | 76% | 2329 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 38,174 psi | 61% | 2306 fps | 95.5% |
| Bofors RP3 | <<locked>> | 80% | 29,617 psi | 47% | 2142 fps | 95% |
| Hodgdon Benchmark | <<locked>> | 80% | 41,162 psi | 66% | 2277 fps | 99% |
| Hodgdon BL-C2 | <<locked>> | 80% | 36,738 psi | 59% | 2287 fps | 98.2% |
| Hodgdon CFE223 | 59.4 gr | 80% | 40,379 psi | 65% | 2402 fps | 96.8% |
| Hodgdon H322 | <<locked>> | 80% | 44,237 psi | 71% | 2372 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 44,875 psi | 72% | 2392 fps | 100% |
| Hodgdon H380 | <<locked>> | 88% | 39,972 psi | 64% | 2333 fps | 95.3% |
| Hodgdon H4895 | <<locked>> | 80% | 37,173 psi | 60% | 2274 fps | 97.1% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 33,344 psi | 53% | 2224 fps | 95.4% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 33,112 psi | 53% | 2234 fps | 96.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,715 psi | 41% | 1339 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 35,810 psi | 57% | 2231 fps | 96.6% |
| IMR 3031 | <<locked>> | 80% | 35,882 psi | 58% | 2277 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 35,143 psi | 56% | 2205 fps | 95.3% |
| IMR 4166 Enduron | <<locked>> | 92% | 51,808 psi | 83% | 2454 fps | 95.5% |
| IMR 4198 | <<locked>> | 80% | 46,528 psi | 75% | 2320 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 98% | 50,473 psi | 81% | 2467 fps | 95.1% |
| IMR 4831 | <<locked>> | 98% | 39,073 psi | 63% | 2365 fps | 95.8% |
| IMR 4895 | <<locked>> | 80% | 33,649 psi | 54% | 2224 fps | 95.5% |
| IMR 8208 XBR | <<locked>> | 80% | 38,928 psi | 62% | 2277 fps | 98.2% |
| Lovex D073.5 | <<locked>> | 80% | 43,221 psi | 69% | 2349 fps | 99.5% |
| Lovex D073.6 | <<locked>> | 80% | 35,012 psi | 56% | 2244 fps | 98.7% |
| Lovex S060 | <<locked>> | 80% | 37,826 psi | 61% | 2215 fps | 96.7% |
| Lovex S062 | <<locked>> | 80% | 32,663 psi | 52% | 2165 fps | 96.6% |
| Lovex S065 | <<locked>> | 96% | 43,627 psi | 70% | 2372 fps | 95.2% |
| Norma 200 | <<locked>> | 80% | 51,503 psi | 83% | 2402 fps | 100% |
| Norma 201 | <<locked>> | 80% | 36,245 psi | 58% | 2224 fps | 97.6% |
| Norma 202 | <<locked>> | 80% | 36,230 psi | 58% | 2241 fps | 99.4% |
| Norma 203B | <<locked>> | 82% | 34,345 psi | 55% | 2234 fps | 95.6% |
| Norma URP | <<locked>> | 96% | 38,696 psi | 62% | 2362 fps | 95.3% |
| Ramshot Big Game | <<locked>> | 82% | 33,953 psi | 54% | 2241 fps | 95% |
| Ramshot TAC | <<locked>> | 84% | 44,193 psi | 71% | 2369 fps | 95.6% |
| Ramshot Wild Boar | <<locked>> | 80% | 37,710 psi | 60% | 2287 fps | 96.6% |
| Ramshot X-Terminator | <<locked>> | 80% | 42,250 psi | 68% | 2320 fps | 97.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,802 psi | 41% | 1368 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 43,569 psi | 70% | 2356 fps | 99.7% |
| ReloadSwiss RS 50 | <<locked>> | 92% | 46,485 psi | 75% | 2418 fps | 95.1% |
| ReloadSwiss RS 52 | 57.7 gr | 82% | 36,172 psi | 58% | 2326 fps | 95.5% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 28,123 psi | 45% | 2146 fps | 95.4% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 40,509 psi | 65% | 2425 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 40,059 psi | 64% | 2277 fps | 99.7% |
| Rottweil R 902 | <<locked>> | 80% | 34,447 psi | 55% | 2182 fps | 97.1% |
| Rottweil R 903 | <<locked>> | 84% | 31,749 psi | 51% | 2185 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 96% | 43,627 psi | 70% | 2372 fps | 95.2% |
| Shooters World Match Rifle | <<locked>> | 80% | 35,012 psi | 56% | 2244 fps | 98.7% |
| Shooters World Precision | <<locked>> | 80% | 32,663 psi | 52% | 2165 fps | 96.6% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 46,064 psi | 74% | 2369 fps | 99.1% |
| SNPE Vectan BA6 1/2 | <<locked>> | 80% | 52,837 psi | 85% | 2159 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 80% | 48,747 psi | 78% | 2441 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 35,375 psi | 57% | 2280 fps | 95.7% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 46,296 psi | 74% | 2362 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 42,003 psi | 67% | 2339 fps | 95.6% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 35,534 psi | 57% | 2234 fps | 95.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 37,956 psi | 61% | 2198 fps | 99.5% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 31,053 psi | 50% | 2080 fps | 99.1% |
| Somchem S321 | <<locked>> | 80% | 41,495 psi | 67% | 2346 fps | 98.9% |
| Somchem S335 | <<locked>> | 80% | 37,449 psi | 60% | 2205 fps | 99.8% |
| Somchem S341 | <<locked>> | 80% | 36,260 psi | 58% | 2244 fps | 96.1% |
| Somchem S355 | <<locked>> | 84% | 33,025 psi | 53% | 2195 fps | 95.7% |
| Somchem S365 | <<locked>> | 92% | 30,371 psi | 49% | 2215 fps | 95.8% |
| Vihtavuori N120 | <<locked>> | 80% | 53,040 psi | 85% | 2343 fps | 100% |
| Vihtavuori N130 | <<locked>> | 80% | 43,076 psi | 69% | 2267 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 38,014 psi | 61% | 2201 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 33,214 psi | 53% | 2178 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 34,214 psi | 55% | 2185 fps | 99.3% |
| Vihtavuori N150 | <<locked>> | 80% | 27,528 psi | 44% | 2051 fps | 95.1% |
| Vihtavuori N160 | <<locked>> | 94% | 38,159 psi | 61% | 2313 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 38,769 psi | 62% | 2274 fps | 98.2% |
| Vihtavuori N540 | <<locked>> | 80% | 32,880 psi | 53% | 2172 fps | 98.6% |
| Vihtavuori N550 | <<locked>> | 96% | 39,697 psi | 64% | 2365 fps | 95.4% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 34,389 psi | 55% | 2211 fps | 95.8% |
| Winchester 748 | <<locked>> | 80% | 37,478 psi | 60% | 2306 fps | 98.7% |
| Winchester StaBALL Match | <<locked>> | 80% | 34,432 psi | 55% | 2231 fps | 96.3% |
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 .375 H&H Mag. loaded with the .375 | 275gr | SUS-TAC HP. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 2,687 fps; across all powders the maximum-charge window runs from 1,496 fps to 2,687 fps. Accurate 4350 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 55–90 %, leaving at least 10 % headroom. The 275.0 gr projectile in 0.375" calls for a 1:15.5 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 .375 | 275gr | SUS-TAC HP 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.