Load Specifications
Load data in caliber .375 H&H Mag. with .375 | 270gr | Barnes LRX BT 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, Hodgdon CFE223 and ReloadSwiss RS 52.
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>> | 92% | 55,172 psi | 88% | 2490 fps | 100% |
| Accurate 2200 | <<locked>> | 84% | 56,202 psi | 90% | 2585 fps | 99% |
| Accurate 2230 | <<locked>> | 82% | 52,982 psi | 85% | 2543 fps | 98.9% |
| Accurate 2460 | <<locked>> | 88% | 53,780 psi | 86% | 2516 fps | 100% |
| Accurate 2495 | <<locked>> | 98% | 54,824 psi | 88% | 2543 fps | 100% |
| Accurate 2520 | <<locked>> | 92% | 52,837 psi | 85% | 2552 fps | 100% |
| Accurate 2520 | <<locked>> | 92% | 52,837 psi | 85% | 2552 fps | 100% |
| Accurate 4064ᴾ | <<locked>> | 100% | 54,346 psi | 87% | 2575 fps | 100% |
| Accurate LT-30 | <<locked>> | 86% | 56,072 psi | 90% | 2448 fps | 100% |
| Accurate LT-32 | <<locked>> | 84% | 53,171 psi | 85% | 2428 fps | 100% |
| ADI AR 2206H | <<locked>> | 94% | 54,143 psi | 87% | 2572 fps | 99.3% |
| ADI AR 2207 | <<locked>> | 82% | 54,041 psi | 87% | 2425 fps | 100% |
| ADI AR 2208ᴾ | <<locked>> | 100% | 55,245 psi | 89% | 2566 fps | 99% |
| ADI AR 2219 | <<locked>> | 86% | 56,159 psi | 90% | 2559 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 92% | 53,853 psi | 86% | 2536 fps | 99.8% |
| Alliant AR-Comp | <<locked>> | 92% | 52,953 psi | 85% | 2520 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 96% | 53,766 psi | 86% | 2671 fps | 98.8% |
| Alliant Reloder- TS 15.5ᴾ | <<locked>> | 100% | 53,954 psi | 87% | 2585 fps | 99.7% |
| Alliant Reloder-10x | <<locked>> | 88% | 55,477 psi | 89% | 2503 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 98% | 54,911 psi | 88% | 2602 fps | 99.1% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 41,626 psi | 67% | 2438 fps | 95.9% |
| Alliant Reloder-17ᴾ | <<locked>> | 100% | 47,630 psi | 76% | 2579 fps | 99% |
| Alliant Reloder-7 | <<locked>> | 82% | 54,969 psi | 88% | 2441 fps | 100% |
| Baschieri & Pellagri 106 | <<locked>> | 86% | 55,143 psi | 88% | 2451 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 94% | 53,853 psi | 86% | 2585 fps | 98.6% |
| Bofors RP3ᴾ | <<locked>> | 100% | 54,041 psi | 87% | 2595 fps | 99.8% |
| Hodgdon Benchmark | <<locked>> | 92% | 56,159 psi | 90% | 2523 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 94% | 55,883 psi | 90% | 2612 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 90% | 54,041 psi | 87% | 2648 fps | 99.1% |
| Hodgdon H322 | <<locked>> | 90% | 53,751 psi | 86% | 2530 fps | 100% |
| Hodgdon H335 | <<locked>> | 86% | 55,361 psi | 89% | 2562 fps | 100% |
| Hodgdon H380ᴾ | <<locked>> | 100% | 56,086 psi | 90% | 2605 fps | 98.3% |
| Hodgdon H4198 | <<locked>> | 84% | 54,694 psi | 88% | 2448 fps | 100% |
| Hodgdon H4895 | <<locked>> | 94% | 54,592 psi | 88% | 2582 fps | 99.6% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 37,768 psi | 61% | 2339 fps | 96.6% |
| Hodgdon LEVERevolutionᴾ | <<locked>> | 100% | 56,246 psi | 90% | 2651 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,011 psi | 55% | 1503 fps | 100% |
| Hodgdon VARGET | <<locked>> | 98% | 54,955 psi | 88% | 2569 fps | 99.6% |
| IMR 3031 | <<locked>> | 98% | 54,882 psi | 88% | 2589 fps | 100% |
| IMR 4064ᴾ | <<locked>> | 100% | 53,417 psi | 86% | 2533 fps | 98.9% |
| IMR 4198 | <<locked>> | 88% | 56,202 psi | 90% | 2464 fps | 100% |
| IMR 4895 | <<locked>> | 98% | 56,289 psi | 90% | 2631 fps | 99.6% |
| IMR 8208 XBR | <<locked>> | 92% | 53,853 psi | 86% | 2536 fps | 99.8% |
| Lovex D073.4 | <<locked>> | 82% | 53,621 psi | 86% | 2523 fps | 100% |
| Lovex D073.5 | <<locked>> | 88% | 53,592 psi | 86% | 2523 fps | 100% |
| Lovex D073.6 | <<locked>> | 96% | 56,347 psi | 90% | 2595 fps | 100% |
| Lovex S060 | <<locked>> | 94% | 54,940 psi | 88% | 2510 fps | 99.4% |
| Lovex S062 | <<locked>> | 98% | 53,621 psi | 86% | 2546 fps | 99.8% |
| Norma 200 | <<locked>> | 84% | 55,143 psi | 88% | 2474 fps | 100% |
| Norma 201 | <<locked>> | 96% | 56,246 psi | 90% | 2569 fps | 99.9% |
| Norma 202 | <<locked>> | 94% | 53,171 psi | 85% | 2533 fps | 100% |
| Norma 203B | <<locked>> | 98% | 53,983 psi | 87% | 2592 fps | 99.4% |
| Ramshot Big Game | <<locked>> | 98% | 54,549 psi | 87% | 2618 fps | 99.3% |
| Ramshot TAC | <<locked>> | 92% | 54,491 psi | 87% | 2546 fps | 97.4% |
| Ramshot Wild Boar | <<locked>> | 92% | 53,258 psi | 85% | 2566 fps | 99.2% |
| Ramshot X-Terminator | <<locked>> | 90% | 55,390 psi | 89% | 2539 fps | 99.3% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,316 psi | 55% | 1539 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 88% | 53,809 psi | 86% | 2526 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 98% | 53,534 psi | 86% | 2543 fps | 96.3% |
| ReloadSwiss RS 52 | <<locked>> | 96% | 54,723 psi | 88% | 2664 fps | 99.1% |
| ReloadSwiss RS 60ᴾ | <<locked>> | 100% | 50,995 psi | 82% | 2641 fps | 100% |
| Rottweil R 901 | <<locked>> | 92% | 53,751 psi | 86% | 2513 fps | 100% |
| Rottweil R 902 | <<locked>> | 96% | 53,127 psi | 85% | 2520 fps | 99.8% |
| Rottweil R 903ᴾ | <<locked>> | 100% | 50,024 psi | 80% | 2533 fps | 99.3% |
| Shooters World AR Plus | <<locked>> | 82% | 53,621 psi | 86% | 2523 fps | 100% |
| Shooters World Match Rifle | <<locked>> | 96% | 56,347 psi | 90% | 2595 fps | 100% |
| Shooters World Precision | <<locked>> | 98% | 53,621 psi | 86% | 2546 fps | 99.8% |
| Shooters World Tactical Rifle | <<locked>> | 86% | 53,780 psi | 86% | 2497 fps | 99.7% |
| SNPE Vectan BA6 1/2 | <<locked>> | 82% | 53,795 psi | 86% | 2192 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 84% | 52,982 psi | 85% | 2526 fps | 100% |
| SNPE Vectan SP 11ᴾ | <<locked>> | 100% | 52,547 psi | 84% | 2595 fps | 99.1% |
| SNPE Vectan SP 3 | <<locked>> | 86% | 53,156 psi | 85% | 2480 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 94% | 55,767 psi | 89% | 2569 fps | 98.1% |
| SNPE Vectan SP 9 | <<locked>> | 96% | 56,217 psi | 90% | 2595 fps | 99.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 94% | 55,564 psi | 89% | 2480 fps | 100% |
| SNPE Vectan Tubal 5000ᴾ | <<locked>> | 100% | 54,766 psi | 88% | 2474 fps | 100% |
| Somchem S321 | <<locked>> | 90% | 54,868 psi | 88% | 2569 fps | 99.9% |
| Somchem S335 | <<locked>> | 94% | 54,288 psi | 87% | 2480 fps | 100% |
| Somchem S341 | <<locked>> | 94% | 55,143 psi | 88% | 2566 fps | 99.3% |
| Somchem S355ᴾ | <<locked>> | 100% | 51,082 psi | 82% | 2536 fps | 99.3% |
| Somchem S365ᴾ | <<locked>> | 100% | 36,477 psi | 58% | 2379 fps | 97.8% |
| Unknown powderᴾ | <<locked>> | 100% | 45,629 psi | 73% | 2490 fps | 96.1% |
| Vihtavuori N120 | <<locked>> | 82% | 53,998 psi | 87% | 2379 fps | 100% |
| Vihtavuori N130 | <<locked>> | 90% | 55,535 psi | 89% | 2454 fps | 100% |
| Vihtavuori N133 | <<locked>> | 94% | 55,347 psi | 89% | 2470 fps | 100% |
| Vihtavuori N135 | <<locked>> | 98% | 55,158 psi | 88% | 2533 fps | 100% |
| Vihtavuori N140 | <<locked>> | 96% | 53,751 psi | 86% | 2513 fps | 100% |
| Vihtavuori N150ᴾ | <<locked>> | 100% | 49,313 psi | 79% | 2477 fps | 99.7% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 43,656 psi | 70% | 2434 fps | 96.2% |
| Vihtavuori N530 | <<locked>> | 92% | 54,534 psi | 87% | 2539 fps | 99.9% |
| Vihtavuori N540 | <<locked>> | 98% | 55,390 psi | 89% | 2556 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 42,322 psi | 68% | 2434 fps | 95.8% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 45,107 psi | 72% | 2428 fps | 98.4% |
| Winchester 748 | <<locked>> | 90% | 53,969 psi | 87% | 2589 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 88% | 54,462 psi | 87% | 2585 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% | 37,811 psi | 61% | 2244 fps | 100% |
| Accurate 2200 | <<locked>> | 80% | 49,008 psi | 79% | 2480 fps | 98% |
| Accurate 2230 | <<locked>> | 80% | 49,429 psi | 79% | 2490 fps | 98.4% |
| Accurate 2460 | <<locked>> | 80% | 40,814 psi | 65% | 2329 fps | 99.6% |
| Accurate 2495 | <<locked>> | 80% | 29,892 psi | 48% | 2152 fps | 99.7% |
| Accurate 2520 | <<locked>> | 80% | 34,809 psi | 56% | 2267 fps | 98.5% |
| Accurate 2520 | <<locked>> | 80% | 34,809 psi | 56% | 2267 fps | 98.5% |
| Accurate 4064 | <<locked>> | 80% | 28,355 psi | 45% | 2133 fps | 97.7% |
| Accurate LT-30 | <<locked>> | 80% | 46,615 psi | 75% | 2323 fps | 100% |
| Accurate LT-32 | <<locked>> | 80% | 46,992 psi | 75% | 2343 fps | 99.9% |
| ADI AR 2206H | <<locked>> | 80% | 34,693 psi | 56% | 2238 fps | 95.3% |
| ADI AR 2207 | <<locked>> | 80% | 50,705 psi | 81% | 2385 fps | 100% |
| ADI AR 2208 | <<locked>> | 88% | 38,203 psi | 61% | 2293 fps | 95.6% |
| ADI AR 2219 | <<locked>> | 80% | 45,919 psi | 74% | 2421 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 80% | 36,709 psi | 59% | 2257 fps | 97.4% |
| Alliant AR-Comp | <<locked>> | 80% | 35,259 psi | 57% | 2267 fps | 100% |
| Alliant Power Pro 2000-MR | 61.5 gr | 86% | 38,218 psi | 61% | 2392 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 32,227 psi | 52% | 2211 fps | 95.6% |
| Alliant Reloder-10x | <<locked>> | 80% | 43,221 psi | 69% | 2336 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 86% | 37,492 psi | 60% | 2316 fps | 95.7% |
| Alliant Reloder-16 | <<locked>> | 98% | 39,189 psi | 63% | 2388 fps | 95% |
| Alliant Reloder-17 | <<locked>> | 90% | 34,214 psi | 55% | 2316 fps | 95.2% |
| Alliant Reloder-7 | <<locked>> | 80% | 51,677 psi | 83% | 2402 fps | 100% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 45,353 psi | 73% | 2323 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 38,508 psi | 62% | 2333 fps | 95.2% |
| Bofors RP3 | <<locked>> | 84% | 31,256 psi | 50% | 2205 fps | 95.4% |
| Hodgdon Benchmark | <<locked>> | 80% | 39,001 psi | 63% | 2260 fps | 98.4% |
| Hodgdon BL-C2 | <<locked>> | 80% | 34,374 psi | 55% | 2264 fps | 97.4% |
| Hodgdon CFE223 | 58.6 gr | 80% | 38,087 psi | 61% | 2375 fps | 95.8% |
| Hodgdon H322 | <<locked>> | 80% | 38,928 psi | 62% | 2310 fps | 99.9% |
| Hodgdon H335 | <<locked>> | 80% | 44,976 psi | 72% | 2418 fps | 100% |
| Hodgdon H380 | <<locked>> | 92% | 42,844 psi | 69% | 2408 fps | 95.7% |
| Hodgdon H4198 | <<locked>> | 80% | 48,501 psi | 78% | 2365 fps | 100% |
| Hodgdon H4895 | <<locked>> | 80% | 34,867 psi | 56% | 2251 fps | 96.1% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 33,359 psi | 53% | 2244 fps | 95% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 31,372 psi | 50% | 2215 fps | 95.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,193 psi | 40% | 1339 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 33,402 psi | 54% | 2201 fps | 95.4% |
| IMR 3031 | <<locked>> | 80% | 30,719 psi | 49% | 2198 fps | 99.4% |
| IMR 4064 | <<locked>> | 88% | 37,072 psi | 59% | 2264 fps | 95.6% |
| IMR 4198 | <<locked>> | 80% | 44,440 psi | 71% | 2313 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 33,605 psi | 54% | 2247 fps | 95.1% |
| IMR 8208 XBR | <<locked>> | 80% | 36,709 psi | 59% | 2257 fps | 97.4% |
| Lovex D073.4 | <<locked>> | 80% | 50,096 psi | 80% | 2477 fps | 100% |
| Lovex D073.5 | <<locked>> | 80% | 40,509 psi | 65% | 2329 fps | 99% |
| Lovex D073.6 | <<locked>> | 80% | 32,605 psi | 52% | 2218 fps | 97.9% |
| Lovex S060 | <<locked>> | 80% | 35,969 psi | 58% | 2198 fps | 95.8% |
| Lovex S062 | <<locked>> | 80% | 30,501 psi | 49% | 2139 fps | 95.4% |
| Norma 200 | <<locked>> | 80% | 48,704 psi | 78% | 2395 fps | 100% |
| Norma 201 | <<locked>> | 80% | 33,982 psi | 54% | 2201 fps | 96.7% |
| Norma 202 | <<locked>> | 80% | 34,011 psi | 55% | 2221 fps | 98.8% |
| Norma 203B | <<locked>> | 84% | 34,345 psi | 55% | 2257 fps | 95.3% |
| Ramshot Big Game | <<locked>> | 86% | 36,376 psi | 58% | 2313 fps | 95.6% |
| Ramshot TAC | <<locked>> | 86% | 44,788 psi | 72% | 2398 fps | 95.4% |
| Ramshot Wild Boar | <<locked>> | 80% | 35,476 psi | 57% | 2267 fps | 95.5% |
| Ramshot X-Terminator | <<locked>> | 80% | 40,030 psi | 64% | 2300 fps | 96.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,367 psi | 41% | 1375 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 41,437 psi | 66% | 2343 fps | 99.3% |
| ReloadSwiss RS 50 | <<locked>> | 96% | 50,111 psi | 80% | 2493 fps | 95.6% |
| ReloadSwiss RS 52 | 58.3 gr | 84% | 36,274 psi | 58% | 2352 fps | 95.2% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 30,095 psi | 48% | 2221 fps | 96.1% |
| Rottweil R 901 | <<locked>> | 80% | 37,318 psi | 60% | 2251 fps | 99.2% |
| Rottweil R 902 | <<locked>> | 80% | 32,213 psi | 52% | 2159 fps | 96% |
| Rottweil R 903 | <<locked>> | 86% | 31,328 psi | 50% | 2201 fps | 95% |
| Shooters World AR Plus | <<locked>> | 80% | 50,096 psi | 80% | 2477 fps | 100% |
| Shooters World Match Rifle | <<locked>> | 80% | 32,605 psi | 52% | 2218 fps | 97.9% |
| Shooters World Precision | <<locked>> | 80% | 30,501 psi | 49% | 2139 fps | 95.4% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 43,729 psi | 70% | 2349 fps | 98.5% |
| SNPE Vectan BA6 1/2 | <<locked>> | 80% | 51,053 psi | 82% | 2159 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 80% | 46,238 psi | 74% | 2428 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 35,389 psi | 57% | 2300 fps | 95.3% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 44,019 psi | 71% | 2352 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 42,351 psi | 68% | 2369 fps | 95.4% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 35,708 psi | 57% | 2260 fps | 95.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 35,868 psi | 58% | 2182 fps | 99.1% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 29,153 psi | 47% | 2060 fps | 98.4% |
| Somchem S321 | <<locked>> | 80% | 39,059 psi | 63% | 2323 fps | 98.2% |
| Somchem S335 | <<locked>> | 80% | 35,288 psi | 57% | 2188 fps | 99.5% |
| Somchem S341 | <<locked>> | 82% | 36,637 psi | 59% | 2274 fps | 95.8% |
| Somchem S355 | <<locked>> | 86% | 32,750 psi | 53% | 2215 fps | 95.3% |
| Somchem S365 | <<locked>> | 94% | 30,153 psi | 48% | 2228 fps | 95.3% |
| Unknown powder | <<locked>> | 98% | 42,641 psi | 68% | 2438 fps | 95.3% |
| Vihtavuori N120 | <<locked>> | 80% | 50,662 psi | 81% | 2339 fps | 100% |
| Vihtavuori N130 | <<locked>> | 80% | 40,886 psi | 66% | 2257 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 35,940 psi | 58% | 2188 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 30,922 psi | 50% | 2159 fps | 99.8% |
| Vihtavuori N140 | <<locked>> | 80% | 31,981 psi | 51% | 2162 fps | 98.6% |
| Vihtavuori N150 | <<locked>> | 84% | 29,167 psi | 47% | 2116 fps | 95.5% |
| Vihtavuori N160 | <<locked>> | 98% | 40,814 psi | 65% | 2385 fps | 95.4% |
| Vihtavuori N530 | <<locked>> | 80% | 36,506 psi | 59% | 2251 fps | 97.4% |
| Vihtavuori N540 | <<locked>> | 80% | 30,734 psi | 49% | 2149 fps | 97.8% |
| Vihtavuori N550 | <<locked>> | 98% | 39,755 psi | 64% | 2388 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 34,563 psi | 55% | 2231 fps | 95.4% |
| Winchester 748 | <<locked>> | 80% | 38,043 psi | 61% | 2339 fps | 98.6% |
| Winchester StaBALL Match | <<locked>> | 80% | 40,451 psi | 65% | 2372 fps | 97.7% |
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 95 powders for .375 H&H Mag. loaded with the .375 | 270gr | Barnes LRX BT. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 2,671 fps; across all powders the maximum-charge window runs from 1,503 fps to 2,671 fps. Accurate 4064 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 270.0 gr projectile in 0.375" calls for a 1:15.5 twist; slower twists will usually not stabilise this weight. Accurate 4064, ADI AR 2208, Alliant Reloder- TS 15.5 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 CFE223, ReloadSwiss RS 52 rank at the top here: for .375 H&H Mag. with the .375 | 270gr | Barnes LRX BT 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.