Load Specifications
Load data in caliber .375 Blaser Mag. with .375 | 250gr | Alaska Bullet Works Kodiak SP SPBC 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, Hodgdon Superformance and ReloadSwiss RS 60.
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: 25.6"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 84% | 54,012 psi | 89% | 2720 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 52,446 psi | 86% | 2743 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 52,489 psi | 86% | 2792 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 52,489 psi | 86% | 2792 fps | 100% |
| Accurate 2700 | <<locked>> | 92% | 52,837 psi | 87% | 2740 fps | 96.5% |
| Accurate 4064 | <<locked>> | 90% | 52,547 psi | 86% | 2789 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 51,822 psi | 85% | 2864 fps | 99.4% |
| ADI AR 2206H | <<locked>> | 86% | 53,200 psi | 87% | 2822 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 92% | 54,128 psi | 89% | 2818 fps | 99.7% |
| ADI Benchmark 8208 | <<locked>> | 84% | 52,257 psi | 86% | 2772 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 52,707 psi | 87% | 2746 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 52,388 psi | 86% | 2930 fps | 99.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 54,070 psi | 89% | 2841 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 90% | 54,549 psi | 90% | 2861 fps | 99.8% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 53,388 psi | 88% | 2923 fps | 99.7% |
| Alliant Reloder-17 | <<locked>> | 96% | 54,563 psi | 90% | 2959 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 38,159 psi | 63% | 2657 fps | 98.5% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 42,467 psi | 70% | 2812 fps | 97.7% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 52,794 psi | 87% | 2831 fps | 99.5% |
| Bofors RP3 | <<locked>> | 92% | 54,549 psi | 90% | 2858 fps | 100% |
| Bofors RP7 | <<locked>> | 96% | 54,810 psi | 90% | 2825 fps | 97.2% |
| Hodgdon Benchmark | <<locked>> | 84% | 53,882 psi | 88% | 2753 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 54,781 psi | 90% | 2851 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 53,142 psi | 87% | 2894 fps | 99.8% |
| Hodgdon H322 | <<locked>> | 82% | 52,199 psi | 86% | 2756 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 51,982 psi | 85% | 2815 fps | 99% |
| Hodgdon H414 | <<locked>> | 94% | 52,939 psi | 87% | 2887 fps | 97.6% |
| Hodgdon H4350 | <<locked>> | 98% | 53,693 psi | 88% | 2848 fps | 96.4% |
| Hodgdon H4895 | <<locked>> | 86% | 53,693 psi | 88% | 2831 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 49,588 psi | 81% | 2799 fps | 99.9% |
| Hodgdon LEVERevolution | <<locked>> | 90% | 52,765 psi | 87% | 2861 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 51,895 psi | 85% | 2890 fps | 96.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,462 psi | 58% | 1726 fps | 100% |
| Hodgdon VARGET | <<locked>> | 90% | 53,751 psi | 88% | 2815 fps | 100% |
| IMR 3031 | <<locked>> | 88% | 51,938 psi | 85% | 2792 fps | 100% |
| IMR 4064 | <<locked>> | 92% | 52,910 psi | 87% | 2789 fps | 99.7% |
| IMR 4166 Enduron | <<locked>> | 92% | 52,402 psi | 86% | 2759 fps | 97.3% |
| IMR 4350ᴾ | <<locked>> | 100% | 54,810 psi | 90% | 2848 fps | 97.3% |
| IMR 4451 Enduron | <<locked>> | 94% | 53,403 psi | 88% | 2805 fps | 97.4% |
| IMR 4831ᴾ | <<locked>> | 100% | 46,630 psi | 77% | 2762 fps | 98.8% |
| IMR 4895 | <<locked>> | 88% | 52,460 psi | 86% | 2841 fps | 99.9% |
| IMR 8208 XBR | <<locked>> | 84% | 52,257 psi | 86% | 2772 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 52,678 psi | 86% | 2795 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 52,881 psi | 87% | 2749 fps | 99.9% |
| Lovex S062 | <<locked>> | 90% | 53,301 psi | 88% | 2799 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 52,576 psi | 86% | 2799 fps | 98.5% |
| Lovex S070 | <<locked>> | 98% | 53,417 psi | 88% | 2831 fps | 97.8% |
| Norma 201 | <<locked>> | 86% | 51,967 psi | 85% | 2766 fps | 100% |
| Norma 202 | <<locked>> | 86% | 52,373 psi | 86% | 2769 fps | 100% |
| Norma 203B | <<locked>> | 90% | 53,722 psi | 88% | 2848 fps | 99.9% |
| Norma URPᴾ | <<locked>> | 100% | 54,491 psi | 89% | 2904 fps | 99.6% |
| Ramshot Big Game | <<locked>> | 90% | 54,157 psi | 89% | 2871 fps | 99.9% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 53,432 psi | 88% | 2900 fps | 98.4% |
| Ramshot TAC | <<locked>> | 84% | 52,301 psi | 86% | 2785 fps | 98.6% |
| Ramshot Wild Boar | <<locked>> | 84% | 51,880 psi | 85% | 2805 fps | 99.8% |
| Ramshot X-Terminator | <<locked>> | 82% | 52,968 psi | 87% | 2772 fps | 99.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,795 psi | 59% | 1762 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 54,984 psi | 90% | 2802 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 52,373 psi | 86% | 2795 fps | 97.9% |
| ReloadSwiss RS 52 | <<locked>> | 88% | 54,955 psi | 90% | 2930 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 54,433 psi | 89% | 2963 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 51,503 psi | 85% | 2884 fps | 99.2% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 51,430 psi | 84% | 2910 fps | 99% |
| Rottweil R 901 | <<locked>> | 84% | 52,953 psi | 87% | 2749 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 52,388 psi | 86% | 2762 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 54,418 psi | 89% | 2848 fps | 100% |
| Rottweil R 907 | <<locked>> | 96% | 54,810 psi | 90% | 2825 fps | 97.2% |
| Shooters World Long Rifle | <<locked>> | 96% | 52,576 psi | 86% | 2799 fps | 98.5% |
| Shooters World Match Rifle | <<locked>> | 86% | 52,678 psi | 86% | 2795 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 53,301 psi | 88% | 2799 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 53,417 psi | 88% | 2831 fps | 97.8% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 52,620 psi | 86% | 2858 fps | 99.9% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 54,230 psi | 89% | 2818 fps | 99.2% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 54,969 psi | 90% | 2841 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 53,490 psi | 88% | 2707 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 53,490 psi | 88% | 2703 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 52,794 psi | 87% | 2749 fps | 97.4% |
| Somchem S321 | <<locked>> | 82% | 53,127 psi | 87% | 2802 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 52,895 psi | 87% | 2707 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 53,896 psi | 88% | 2808 fps | 99.9% |
| Somchem S355 | <<locked>> | 94% | 54,607 psi | 90% | 2844 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 48,878 psi | 80% | 2854 fps | 100% |
| Unknown powder | <<locked>> | 96% | 52,214 psi | 86% | 2861 fps | 99% |
| Vihtavuori N130 | <<locked>> | 82% | 53,272 psi | 87% | 2671 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 53,722 psi | 88% | 2694 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 52,098 psi | 86% | 2733 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 52,924 psi | 87% | 2749 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 52,794 psi | 87% | 2776 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 53,650 psi | 88% | 2851 fps | 99.4% |
| Vihtavuori N530 | <<locked>> | 84% | 52,562 psi | 86% | 2772 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 54,331 psi | 89% | 2792 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 52,692 psi | 87% | 2854 fps | 99.3% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 41,524 psi | 68% | 2736 fps | 98.4% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 54,215 psi | 89% | 2831 fps | 100% |
| Winchester 748 | <<locked>> | 82% | 52,765 psi | 87% | 2822 fps | 100% |
| Winchester 760 | <<locked>> | 94% | 52,939 psi | 87% | 2887 fps | 97.6% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 34,055 psi | 56% | 2651 fps | 98.2% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 25.6"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 47,732 psi | 78% | 2628 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 40,509 psi | 67% | 2556 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 45,861 psi | 75% | 2690 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 45,861 psi | 75% | 2690 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 46,398 psi | 76% | 2635 fps | 95.1% |
| Accurate 4064 | <<locked>> | 80% | 38,276 psi | 63% | 2552 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 34,330 psi | 56% | 2533 fps | 95.6% |
| ADI AR 2206H | <<locked>> | 80% | 43,961 psi | 72% | 2664 fps | 99.1% |
| ADI AR 2208 | <<locked>> | 80% | 37,362 psi | 61% | 2513 fps | 97.1% |
| ADI Benchmark 8208 | <<locked>> | 80% | 46,006 psi | 76% | 2671 fps | 99.8% |
| Alliant AR-Comp | <<locked>> | 80% | 46,224 psi | 76% | 2657 fps | 100% |
| Alliant Power Pro 2000-MR | 75.8 gr | 80% | 39,972 psi | 66% | 2690 fps | 97.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 37,028 psi | 61% | 2536 fps | 98.5% |
| Alliant Reloder-15 | <<locked>> | 80% | 39,697 psi | 65% | 2598 fps | 97.9% |
| Alliant Reloder-16 | <<locked>> | 86% | 34,751 psi | 57% | 2543 fps | 95.7% |
| Alliant Reloder-17 | <<locked>> | 80% | 31,908 psi | 52% | 2500 fps | 96.5% |
| Alliant Reloder-23 | <<locked>> | 92% | 29,849 psi | 49% | 2444 fps | 95.3% |
| Alliant Reloder-26 | <<locked>> | 96% | 36,825 psi | 60% | 2680 fps | 95.7% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 43,091 psi | 71% | 2664 fps | 98.2% |
| Bofors RP3 | <<locked>> | 80% | 36,579 psi | 60% | 2539 fps | 98.5% |
| Bofors RP7 | <<locked>> | 90% | 45,382 psi | 75% | 2664 fps | 95.1% |
| Hodgdon Benchmark | <<locked>> | 80% | 47,732 psi | 78% | 2657 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 44,860 psi | 74% | 2694 fps | 99.9% |
| Hodgdon CFE223 | <<locked>> | 80% | 49,385 psi | 81% | 2835 fps | 99.5% |
| Hodgdon H322 | <<locked>> | 80% | 48,849 psi | 80% | 2707 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 37,492 psi | 62% | 2543 fps | 96% |
| Hodgdon H414 | <<locked>> | 88% | 43,047 psi | 71% | 2710 fps | 95.3% |
| Hodgdon H4350 | <<locked>> | 96% | 50,560 psi | 83% | 2795 fps | 95.7% |
| Hodgdon H4895 | <<locked>> | 80% | 44,324 psi | 73% | 2674 fps | 99.4% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 29,791 psi | 49% | 2385 fps | 95.6% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 38,029 psi | 62% | 2598 fps | 98.8% |
| Hodgdon Superformance | 90.7 gr | 92% | 45,107 psi | 74% | 2766 fps | 95.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,411 psi | 43% | 1539 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 39,494 psi | 65% | 2562 fps | 98.7% |
| IMR 3031 | <<locked>> | 80% | 40,350 psi | 66% | 2605 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 36,738 psi | 60% | 2490 fps | 97.2% |
| IMR 4166 Enduron | <<locked>> | 86% | 43,845 psi | 72% | 2608 fps | 95.3% |
| IMR 4350 | <<locked>> | 94% | 45,440 psi | 75% | 2690 fps | 95.2% |
| IMR 4451 Enduron | <<locked>> | 88% | 44,425 psi | 73% | 2648 fps | 95.4% |
| IMR 4831 | <<locked>> | 90% | 34,026 psi | 56% | 2507 fps | 95.6% |
| IMR 4895 | <<locked>> | 80% | 40,640 psi | 67% | 2628 fps | 98.6% |
| IMR 8208 XBR | <<locked>> | 80% | 46,006 psi | 76% | 2671 fps | 99.8% |
| Lovex D073.6 | <<locked>> | 80% | 43,062 psi | 71% | 2641 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 44,106 psi | 72% | 2598 fps | 99.1% |
| Lovex S062 | <<locked>> | 80% | 39,189 psi | 64% | 2552 fps | 99.2% |
| Lovex S065 | <<locked>> | 86% | 38,754 psi | 64% | 2543 fps | 95.4% |
| Lovex S070 | <<locked>> | 90% | 41,539 psi | 68% | 2621 fps | 95% |
| Norma 201 | <<locked>> | 80% | 43,163 psi | 71% | 2615 fps | 99.6% |
| Norma 202 | <<locked>> | 80% | 43,439 psi | 71% | 2625 fps | 100% |
| Norma 203B | <<locked>> | 80% | 39,102 psi | 64% | 2585 fps | 98.3% |
| Norma URP | <<locked>> | 86% | 34,650 psi | 57% | 2530 fps | 95.5% |
| Ramshot Big Game | <<locked>> | 80% | 38,653 psi | 63% | 2598 fps | 98% |
| Ramshot Hunter | <<locked>> | 92% | 41,249 psi | 68% | 2680 fps | 95.7% |
| Ramshot TAC | <<locked>> | 80% | 45,992 psi | 76% | 2677 fps | 97.5% |
| Ramshot Wild Boar | <<locked>> | 80% | 45,411 psi | 75% | 2697 fps | 99.3% |
| Ramshot X-Terminator | <<locked>> | 80% | 49,632 psi | 81% | 2720 fps | 99.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,643 psi | 44% | 1575 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 51,547 psi | 85% | 2749 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 40,422 psi | 66% | 2579 fps | 95.1% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 41,568 psi | 68% | 2697 fps | 98.3% |
| ReloadSwiss RS 60 | 74.6 gr | 80% | 33,953 psi | 56% | 2566 fps | 99.3% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 34,069 psi | 56% | 2546 fps | 95% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 36,651 psi | 60% | 2605 fps | 95% |
| Rottweil R 901 | <<locked>> | 80% | 47,123 psi | 77% | 2657 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 41,118 psi | 68% | 2569 fps | 99.4% |
| Rottweil R 903 | <<locked>> | 80% | 34,360 psi | 56% | 2484 fps | 97.7% |
| Rottweil R 907 | <<locked>> | 90% | 45,382 psi | 75% | 2664 fps | 95.1% |
| Shooters World Long Rifle | <<locked>> | 86% | 38,754 psi | 64% | 2543 fps | 95.4% |
| Shooters World Match Rifle | <<locked>> | 80% | 43,062 psi | 71% | 2641 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 39,189 psi | 64% | 2552 fps | 99.2% |
| Shooters World SW4350 | <<locked>> | 90% | 41,539 psi | 68% | 2621 fps | 95% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 35,317 psi | 58% | 2530 fps | 97.2% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 44,222 psi | 73% | 2648 fps | 97.7% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 42,409 psi | 70% | 2631 fps | 98.8% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 44,556 psi | 73% | 2572 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 37,028 psi | 61% | 2441 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 43,497 psi | 71% | 2592 fps | 95.3% |
| Somchem S321 | <<locked>> | 80% | 49,734 psi | 82% | 2749 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 44,106 psi | 72% | 2572 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 43,859 psi | 72% | 2648 fps | 99% |
| Somchem S355 | <<locked>> | 80% | 35,331 psi | 58% | 2490 fps | 97.7% |
| Somchem S365 | <<locked>> | 80% | 25,556 psi | 42% | 2316 fps | 95% |
| Unknown powder | <<locked>> | 84% | 35,433 psi | 58% | 2536 fps | 95% |
| Vihtavuori N130 | <<locked>> | 80% | 50,299 psi | 83% | 2628 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 44,860 psi | 74% | 2562 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 40,538 psi | 67% | 2552 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 41,002 psi | 67% | 2559 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 33,475 psi | 55% | 2428 fps | 98.4% |
| Vihtavuori N160 | <<locked>> | 84% | 34,011 psi | 56% | 2480 fps | 95.2% |
| Vihtavuori N530 | <<locked>> | 80% | 46,151 psi | 76% | 2667 fps | 99.9% |
| Vihtavuori N540 | <<locked>> | 80% | 39,581 psi | 65% | 2549 fps | 100% |
| Vihtavuori N550 | <<locked>> | 86% | 35,621 psi | 58% | 2533 fps | 95.6% |
| Vihtavuori N555 | <<locked>> | 92% | 31,981 psi | 53% | 2520 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 29,791 psi | 49% | 2349 fps | 95.7% |
| Winchester 748 | <<locked>> | 80% | 49,269 psi | 81% | 2769 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 43,047 psi | 71% | 2710 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 96% | 29,965 psi | 49% | 2520 fps | 95.9% |
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 Blaser Mag. loaded with the .375 | 250gr | Alaska Bullet Works Kodiak SP SPBC. ReloadSwiss RS 60 delivers the highest muzzle velocity at 2,963 fps; across all powders the maximum-charge window runs from 1,726 fps to 2,963 fps. Alliant Reloder-16 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 (420 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.375" calls for a 1:6.0 twist; slower twists will usually not stabilise this weight. Alliant Reloder-16, Alliant Reloder-23, Alliant Reloder-26 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, ReloadSwiss RS 60 rank at the top here: for .375 Blaser Mag. with the .375 | 250gr | Alaska Bullet Works Kodiak SP SPBC 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.