Load Specifications
Load data in caliber .375 Ruger with .375 | 300gr | Swift A-Frame bullet and 99 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 Superformance and Alliant Reloder-17.
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: 23"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 84% | 55,593 psi | 90% | 2349 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 54,462 psi | 88% | 2375 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 56,173 psi | 90% | 2431 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 53,461 psi | 86% | 2375 fps | 97.4% |
| Accurate 3100ᴾ | <<locked>> | 100% | 41,321 psi | 67% | 2290 fps | 96.7% |
| Accurate 4064 | <<locked>> | 90% | 54,447 psi | 88% | 2415 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 53,896 psi | 87% | 2490 fps | 99.8% |
| ADI AR 2206H | <<locked>> | 86% | 54,708 psi | 88% | 2441 fps | 100% |
| ADI AR 2208 | <<locked>> | 92% | 55,593 psi | 90% | 2441 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 84% | 53,635 psi | 86% | 2398 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 54,534 psi | 88% | 2372 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 54,346 psi | 88% | 2546 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 55,854 psi | 90% | 2461 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 88% | 52,808 psi | 85% | 2438 fps | 99.9% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 55,245 psi | 89% | 2539 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 94% | 52,823 psi | 85% | 2523 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 39,508 psi | 64% | 2320 fps | 99.3% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 44,179 psi | 71% | 2457 fps | 98.8% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 54,389 psi | 88% | 2454 fps | 99.9% |
| Bofors RP3 | <<locked>> | 90% | 52,779 psi | 85% | 2431 fps | 100% |
| Bofors RP7 | <<locked>> | 94% | 52,968 psi | 85% | 2408 fps | 97.6% |
| Hodgdon Benchmark | <<locked>> | 84% | 55,506 psi | 89% | 2382 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 84% | 53,055 psi | 85% | 2428 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 54,911 psi | 88% | 2510 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 53,795 psi | 87% | 2444 fps | 99.6% |
| Hodgdon H414 | <<locked>> | 96% | 53,214 psi | 86% | 2487 fps | 98.3% |
| Hodgdon H4350 | <<locked>> | 94% | 53,940 psi | 87% | 2454 fps | 97.2% |
| Hodgdon H4895 | <<locked>> | 86% | 55,303 psi | 89% | 2451 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 51,532 psi | 83% | 2431 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 54,737 psi | 88% | 2480 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 53,693 psi | 86% | 2516 fps | 98% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,636 psi | 57% | 1476 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 53,113 psi | 86% | 2411 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 55,419 psi | 89% | 2431 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 55,114 psi | 89% | 2425 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 88% | 55,158 psi | 89% | 2411 fps | 98.4% |
| IMR 4350 | <<locked>> | 98% | 53,142 psi | 86% | 2428 fps | 97.7% |
| IMR 4451 Enduron | <<locked>> | 94% | 54,911 psi | 88% | 2434 fps | 98.3% |
| IMR 4831ᴾ | <<locked>> | 100% | 54,534 psi | 88% | 2484 fps | 99.9% |
| IMR 4895 | <<locked>> | 88% | 54,157 psi | 87% | 2461 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 53,635 psi | 86% | 2398 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 54,476 psi | 88% | 2418 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 54,288 psi | 87% | 2379 fps | 100% |
| Lovex S062 | <<locked>> | 90% | 55,071 psi | 89% | 2425 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 54,230 psi | 87% | 2428 fps | 99.2% |
| Lovex S070 | <<locked>> | 98% | 55,085 psi | 89% | 2457 fps | 98.6% |
| Norma 201 | <<locked>> | 86% | 53,403 psi | 86% | 2392 fps | 100% |
| Norma 202 | <<locked>> | 86% | 53,998 psi | 87% | 2395 fps | 100% |
| Norma 203B | <<locked>> | 90% | 55,579 psi | 90% | 2470 fps | 100% |
| Norma 204 | <<locked>> | 98% | 53,722 psi | 87% | 2470 fps | 96.5% |
| Norma MRPᴾ | <<locked>> | 100% | 44,077 psi | 71% | 2418 fps | 96.2% |
| Norma URP | <<locked>> | 98% | 52,982 psi | 85% | 2477 fps | 99.7% |
| Ramshot Big Game | <<locked>> | 90% | 56,130 psi | 90% | 2493 fps | 100% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 55,376 psi | 89% | 2523 fps | 99.2% |
| Ramshot TAC | <<locked>> | 84% | 53,838 psi | 87% | 2418 fps | 99.2% |
| Ramshot Wild Boar | <<locked>> | 84% | 53,548 psi | 86% | 2431 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 54,534 psi | 88% | 2402 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,114 psi | 58% | 1512 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 54,128 psi | 87% | 2428 fps | 98.7% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 53,084 psi | 86% | 2490 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 52,663 psi | 85% | 2523 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 53,476 psi | 86% | 2507 fps | 99.7% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 53,345 psi | 86% | 2536 fps | 99.6% |
| Rottweil R 901 | <<locked>> | 84% | 54,534 psi | 88% | 2375 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 54,041 psi | 87% | 2395 fps | 100% |
| Rottweil R 903 | <<locked>> | 92% | 52,663 psi | 85% | 2425 fps | 100% |
| Rottweil R 907 | <<locked>> | 94% | 52,968 psi | 85% | 2408 fps | 97.6% |
| Shooters World Long Rifle | <<locked>> | 96% | 54,230 psi | 87% | 2428 fps | 99.2% |
| Shooters World Match Rifle | <<locked>> | 86% | 54,476 psi | 88% | 2418 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 55,071 psi | 89% | 2425 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 55,085 psi | 89% | 2457 fps | 98.6% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 54,288 psi | 87% | 2477 fps | 100% |
| SNPE Vectan SP 3 | <<locked>> | 86% | 55,274 psi | 89% | 2326 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 55,970 psi | 90% | 2444 fps | 99.7% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 53,026 psi | 85% | 2418 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 55,013 psi | 89% | 2339 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 55,288 psi | 89% | 2339 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 54,621 psi | 88% | 2388 fps | 98.3% |
| Somchem S321 | <<locked>> | 82% | 54,824 psi | 88% | 2428 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 54,273 psi | 87% | 2336 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 55,463 psi | 89% | 2434 fps | 100% |
| Somchem S355 | <<locked>> | 92% | 53,156 psi | 86% | 2425 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 51,010 psi | 82% | 2480 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 47,384 psi | 76% | 2379 fps | 96.5% |
| Vihtavuori N130 | <<locked>> | 82% | 54,824 psi | 88% | 2306 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 55,274 psi | 89% | 2326 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 53,650 psi | 86% | 2359 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 54,534 psi | 88% | 2375 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 54,520 psi | 88% | 2405 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 55,506 psi | 89% | 2474 fps | 99.8% |
| Vihtavuori N530 | <<locked>> | 84% | 54,041 psi | 87% | 2395 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 56,144 psi | 90% | 2415 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 54,607 psi | 88% | 2484 fps | 99.7% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 43,381 psi | 70% | 2382 fps | 99.2% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 55,912 psi | 90% | 2457 fps | 100% |
| Winchester 748 | <<locked>> | 84% | 54,172 psi | 87% | 2441 fps | 100% |
| Winchester 760 | <<locked>> | 96% | 53,432 psi | 86% | 2490 fps | 98.3% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 35,360 psi | 57% | 2326 fps | 99.4% |
| Winchester StaBALL Match | <<locked>> | 86% | 52,910 psi | 85% | 2425 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 23"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 49,240 psi | 79% | 2274 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 41,916 psi | 68% | 2215 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 48,921 psi | 79% | 2343 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 44,048 psi | 71% | 2238 fps | 95.3% |
| Accurate 3100 | <<locked>> | 96% | 35,969 psi | 58% | 2198 fps | 95.1% |
| Accurate 4064 | <<locked>> | 80% | 39,639 psi | 64% | 2211 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 31,096 psi | 50% | 2110 fps | 95.2% |
| ADI AR 2206H | <<locked>> | 80% | 45,440 psi | 73% | 2313 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 80% | 38,653 psi | 62% | 2185 fps | 98.1% |
| ADI Benchmark 8208 | <<locked>> | 80% | 47,471 psi | 76% | 2313 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 47,993 psi | 77% | 2297 fps | 100% |
| Alliant Power Pro 2000-MR | 65.7 gr | 80% | 41,249 psi | 66% | 2343 fps | 98.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 38,319 psi | 62% | 2205 fps | 99.2% |
| Alliant Reloder-15 | <<locked>> | 80% | 41,104 psi | 66% | 2257 fps | 98.8% |
| Alliant Reloder-16 | <<locked>> | 82% | 31,720 psi | 51% | 2123 fps | 95.4% |
| Alliant Reloder-17 | 64.7 gr | 80% | 33,011 psi | 53% | 2182 fps | 97.8% |
| Alliant Reloder-23 | <<locked>> | 88% | 27,441 psi | 44% | 2044 fps | 95% |
| Alliant Reloder-26 | <<locked>> | 92% | 33,388 psi | 54% | 2238 fps | 95.3% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 44,614 psi | 72% | 2316 fps | 99% |
| Bofors RP3 | <<locked>> | 80% | 37,869 psi | 61% | 2208 fps | 99.3% |
| Bofors RP7 | <<locked>> | 88% | 44,077 psi | 71% | 2274 fps | 95.6% |
| Hodgdon Benchmark | <<locked>> | 80% | 49,037 psi | 79% | 2300 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 46,354 psi | 75% | 2336 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 80% | 51,169 psi | 82% | 2461 fps | 99.9% |
| Hodgdon H380 | <<locked>> | 80% | 38,740 psi | 62% | 2211 fps | 97.2% |
| Hodgdon H414 | <<locked>> | 88% | 40,915 psi | 66% | 2297 fps | 95.6% |
| Hodgdon H4350 | <<locked>> | 88% | 44,730 psi | 72% | 2316 fps | 95% |
| Hodgdon H4895 | <<locked>> | 80% | 45,832 psi | 74% | 2320 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 27,311 psi | 44% | 1995 fps | 95.4% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 41,727 psi | 67% | 2297 fps | 99.7% |
| Hodgdon Superformance | 76.9 gr | 90% | 43,424 psi | 70% | 2359 fps | 95.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,542 psi | 43% | 1319 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 43,976 psi | 71% | 2280 fps | 99.7% |
| IMR 3031 | <<locked>> | 80% | 45,571 psi | 73% | 2310 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 40,567 psi | 65% | 2211 fps | 98.7% |
| IMR 4166 Enduron | <<locked>> | 80% | 43,033 psi | 69% | 2231 fps | 95.9% |
| IMR 4350 | <<locked>> | 92% | 44,092 psi | 71% | 2293 fps | 95.7% |
| IMR 4451 Enduron | <<locked>> | 84% | 40,524 psi | 65% | 2211 fps | 95.1% |
| IMR 4831 | <<locked>> | 84% | 32,329 psi | 52% | 2123 fps | 95.8% |
| IMR 4895 | <<locked>> | 80% | 42,119 psi | 68% | 2283 fps | 99.3% |
| IMR 8208 XBR | <<locked>> | 80% | 47,471 psi | 76% | 2313 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 44,512 psi | 72% | 2290 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 45,310 psi | 73% | 2254 fps | 99.6% |
| Lovex S062 | <<locked>> | 80% | 40,466 psi | 65% | 2215 fps | 99.7% |
| Lovex S065 | <<locked>> | 82% | 35,317 psi | 57% | 2123 fps | 95.1% |
| Lovex S070 | <<locked>> | 88% | 40,437 psi | 65% | 2238 fps | 95.6% |
| Norma 201 | <<locked>> | 80% | 44,411 psi | 72% | 2267 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 44,831 psi | 72% | 2274 fps | 100% |
| Norma 203B | <<locked>> | 80% | 40,480 psi | 65% | 2247 fps | 99% |
| Norma 204 | <<locked>> | 96% | 50,198 psi | 81% | 2421 fps | 95.8% |
| Norma MRP | <<locked>> | 98% | 41,249 psi | 66% | 2365 fps | 95.3% |
| Norma URP | <<locked>> | 82% | 31,575 psi | 51% | 2113 fps | 95.2% |
| Ramshot Big Game | <<locked>> | 80% | 39,987 psi | 64% | 2260 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 88% | 37,420 psi | 60% | 2238 fps | 95.3% |
| Ramshot TAC | <<locked>> | 80% | 47,326 psi | 76% | 2323 fps | 98.4% |
| Ramshot Wild Boar | <<locked>> | 80% | 46,876 psi | 76% | 2339 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 80% | 51,024 psi | 82% | 2356 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,890 psi | 43% | 1352 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 39,030 psi | 63% | 2195 fps | 95.5% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 43,337 psi | 70% | 2349 fps | 99.1% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 35,172 psi | 57% | 2238 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 33,025 psi | 53% | 2172 fps | 95.6% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 35,520 psi | 57% | 2224 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 48,457 psi | 78% | 2300 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 42,395 psi | 68% | 2228 fps | 99.8% |
| Rottweil R 903 | <<locked>> | 80% | 35,723 psi | 58% | 2162 fps | 98.7% |
| Rottweil R 907 | <<locked>> | 88% | 44,077 psi | 71% | 2274 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 82% | 35,317 psi | 57% | 2123 fps | 95.1% |
| Shooters World Match Rifle | <<locked>> | 80% | 44,512 psi | 72% | 2290 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 40,466 psi | 65% | 2215 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 88% | 40,437 psi | 65% | 2238 fps | 95.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 36,637 psi | 59% | 2205 fps | 98.2% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 46,035 psi | 74% | 2215 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 45,759 psi | 74% | 2303 fps | 98.5% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 43,845 psi | 71% | 2283 fps | 99.4% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 45,716 psi | 74% | 2221 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 38,116 psi | 61% | 2113 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 39,320 psi | 63% | 2162 fps | 95% |
| Somchem S321 | <<locked>> | 80% | 51,401 psi | 83% | 2382 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 45,310 psi | 73% | 2224 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 45,469 psi | 73% | 2300 fps | 99.6% |
| Somchem S355 | <<locked>> | 80% | 36,492 psi | 59% | 2165 fps | 98.6% |
| Somchem S365 | <<locked>> | 80% | 26,498 psi | 43% | 2024 fps | 96.6% |
| Somchem S385 | <<locked>> | 96% | 41,611 psi | 67% | 2287 fps | 95% |
| Vihtavuori N130 | <<locked>> | 80% | 51,561 psi | 83% | 2267 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 46,035 psi | 74% | 2215 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 41,829 psi | 67% | 2208 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 42,395 psi | 68% | 2218 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 34,708 psi | 56% | 2110 fps | 99.2% |
| Vihtavuori N160 | <<locked>> | 82% | 32,967 psi | 53% | 2116 fps | 95.7% |
| Vihtavuori N530 | <<locked>> | 80% | 47,471 psi | 76% | 2310 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 40,814 psi | 66% | 2211 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 32,460 psi | 52% | 2116 fps | 95.3% |
| Vihtavuori N555 | <<locked>> | 88% | 29,283 psi | 47% | 2110 fps | 95.2% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 30,806 psi | 50% | 2051 fps | 97.1% |
| Winchester 748 | <<locked>> | 80% | 47,166 psi | 76% | 2349 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 41,031 psi | 66% | 2300 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 92% | 27,383 psi | 44% | 2106 fps | 95.4% |
| Winchester StaBALL Match | <<locked>> | 80% | 43,323 psi | 70% | 2287 fps | 99.7% |
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 118 powders for .375 Ruger loaded with the .375 | 300gr | Swift A-Frame. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 2,546 fps; across all powders the maximum-charge window runs from 1,476 fps to 2,546 fps. Accurate 3100 gives the best case fill at 100 %, and 118 of the 118 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (428 MPa), the top charges use 55–90 %, leaving at least 10 % headroom. The 300.0 gr projectile in 0.375" calls for a 1:6.0 twist; slower twists will usually not stabilise this weight. Accurate 3100, ADI AR 2209, ADI AR 2213 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 Superformance, Alliant Reloder-17 rank at the top here: for .375 Ruger with the .375 | 300gr | Swift A-Frame they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, ADI AR 2213, Alliant Reloder-22, Alliant Reloder-25 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.