Load Specifications
Load data in caliber 37XC with .375 | 300gr | NorthFork Bonded Core bullet and 100 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N560, Accurate MAGPRO and Norma MRP.
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: 30"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 82% | 62,395 psi | 90% | 2740 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 59,117 psi | 85% | 2795 fps | 100% |
| Accurate 3100 | <<locked>> | 98% | 59,219 psi | 85% | 2861 fps | 100% |
| Accurate 4064 | <<locked>> | 82% | 59,176 psi | 85% | 2756 fps | 100% |
| Accurate 4350 | <<locked>> | 90% | 60,959 psi | 88% | 2890 fps | 100% |
| Accurate MAGPRO | <<locked>> | 98% | 61,975 psi | 89% | 3035 fps | 99.7% |
| ADI APS 450 | <<locked>> | 84% | 62,917 psi | 90% | 2188 fps | 100% |
| ADI AR 2208 | <<locked>> | 86% | 62,091 psi | 89% | 2844 fps | 100% |
| ADI AR 2209 | <<locked>> | 96% | 61,612 psi | 89% | 2956 fps | 100% |
| ADI AR 2213 | <<locked>> | 98% | 59,306 psi | 85% | 2969 fps | 99.8% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 46,296 psi | 67% | 2759 fps | 98.8% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 41,075 psi | 59% | 2733 fps | 99.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 59,828 psi | 86% | 2818 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 59,886 psi | 86% | 2844 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 92% | 61,627 psi | 89% | 2940 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 59,306 psi | 85% | 2910 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 96% | 60,916 psi | 88% | 2946 fps | 100% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 62,975 psi | 90% | 3015 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 59,857 psi | 86% | 2913 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 51,779 psi | 74% | 2884 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 96% | 60,959 psi | 88% | 3022 fps | 100% |
| Baschieri & Pellagri 109ᴾ | <<locked>> | 100% | 61,163 psi | 88% | 2930 fps | 98.5% |
| Bofors RP15ᴾ | <<locked>> | 100% | 57,711 psi | 83% | 2946 fps | 100% |
| Bofors RP3 | <<locked>> | 84% | 61,134 psi | 88% | 2838 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 47,761 psi | 69% | 2835 fps | 99.3% |
| Bofors RP5ᴾ | <<locked>> | 100% | 62,975 psi | 90% | 3015 fps | 100% |
| Bofors RP7 | <<locked>> | 88% | 59,814 psi | 86% | 2844 fps | 100% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 51,039 psi | 73% | 2841 fps | 99.7% |
| Hodgdon H380 | <<locked>> | 84% | 61,192 psi | 88% | 2864 fps | 100% |
| Hodgdon H414 | <<locked>> | 90% | 62,801 psi | 90% | 2949 fps | 100% |
| Hodgdon H4350 | <<locked>> | 88% | 61,772 psi | 89% | 2907 fps | 100% |
| Hodgdon H4831 | <<locked>> | 96% | 59,408 psi | 85% | 2907 fps | 99.5% |
| Hodgdon H4831 SC | <<locked>> | 98% | 62,178 psi | 89% | 2943 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 62,018 psi | 89% | 2854 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 62,830 psi | 90% | 2884 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 50,749 psi | 73% | 2956 fps | 100% |
| Hodgdon Superformance | <<locked>> | 88% | 59,524 psi | 86% | 2943 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,999 psi | 53% | 1732 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 62,497 psi | 90% | 2838 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 61,612 psi | 89% | 2822 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 60,089 psi | 86% | 2822 fps | 100% |
| IMR 4350 | <<locked>> | 92% | 61,250 psi | 88% | 2881 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 88% | 61,264 psi | 88% | 2864 fps | 100% |
| IMR 4831 | <<locked>> | 92% | 61,163 psi | 88% | 2877 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 61,467 psi | 88% | 2867 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 96% | 60,191 psi | 86% | 2884 fps | 99.6% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 60,843 psi | 87% | 3002 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 36,709 psi | 53% | 2638 fps | 96.7% |
| Lovex S060 | <<locked>> | 82% | 62,424 psi | 90% | 2795 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 62,033 psi | 89% | 2812 fps | 100% |
| Lovex S065 | <<locked>> | 90% | 61,815 psi | 89% | 2854 fps | 100% |
| Lovex S070 | <<locked>> | 90% | 59,857 psi | 86% | 2858 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 52,707 psi | 76% | 2776 fps | 100% |
| Norma 203B | <<locked>> | 82% | 59,234 psi | 85% | 2828 fps | 100% |
| Norma 204 | <<locked>> | 92% | 62,700 psi | 90% | 2946 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 36,608 psi | 53% | 2664 fps | 98.8% |
| Norma MRP | <<locked>> | 96% | 58,900 psi | 85% | 2986 fps | 100% |
| Norma URP | <<locked>> | 92% | 62,932 psi | 90% | 2920 fps | 100% |
| Ramshot Big Game | <<locked>> | 82% | 60,292 psi | 87% | 2854 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 62,004 psi | 89% | 3022 fps | 100% |
| Ramshot Hunter | <<locked>> | 92% | 61,757 psi | 89% | 2936 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 55,738 psi | 80% | 2900 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,768 psi | 54% | 1775 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 60,756 psi | 87% | 2851 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 58,885 psi | 85% | 2897 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 61,046 psi | 88% | 2917 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 59,306 psi | 85% | 2953 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 51,169 psi | 74% | 2953 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 46,035 psi | 66% | 2841 fps | 98% |
| Rottweil R 902 | <<locked>> | 82% | 60,046 psi | 86% | 2772 fps | 100% |
| Rottweil R 903 | <<locked>> | 86% | 61,177 psi | 88% | 2831 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 62,917 psi | 90% | 2923 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 96% | 60,423 psi | 87% | 2933 fps | 100% |
| Rottweil R 907 | <<locked>> | 88% | 59,814 psi | 86% | 2844 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 90% | 61,815 psi | 89% | 2854 fps | 100% |
| Shooters World Precision | <<locked>> | 84% | 62,033 psi | 89% | 2812 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 59,857 psi | 86% | 2858 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 62,830 psi | 90% | 2890 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 61,017 psi | 88% | 2694 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 61,453 psi | 88% | 2815 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 96% | 59,944 psi | 86% | 2930 fps | 100% |
| Somchem S355 | <<locked>> | 86% | 60,698 psi | 87% | 2825 fps | 100% |
| Somchem S361 | <<locked>> | 94% | 61,061 psi | 88% | 2867 fps | 99.6% |
| Somchem S365 | <<locked>> | 92% | 59,466 psi | 85% | 2871 fps | 100% |
| Somchem S385 | <<locked>> | 96% | 61,061 psi | 88% | 2904 fps | 100% |
| Vihtavuori N135 | <<locked>> | 82% | 60,916 psi | 88% | 2720 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 60,858 psi | 87% | 2740 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 62,192 psi | 89% | 2792 fps | 100% |
| Vihtavuori N160 | <<locked>> | 90% | 61,119 psi | 88% | 2861 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 60,437 psi | 87% | 2881 fps | 100% |
| Vihtavuori N540 | <<locked>> | 84% | 62,801 psi | 90% | 2789 fps | 100% |
| Vihtavuori N550 | <<locked>> | 90% | 60,220 psi | 87% | 2874 fps | 100% |
| Vihtavuori N555 | <<locked>> | 98% | 62,424 psi | 90% | 2940 fps | 100% |
| Vihtavuori N560 | <<locked>> | 98% | 62,946 psi | 90% | 3045 fps | 99.9% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 54,404 psi | 78% | 2910 fps | 99.5% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 47,456 psi | 68% | 2851 fps | 97.7% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 60,959 psi | 88% | 2822 fps | 100% |
| Winchester 760 | <<locked>> | 90% | 62,990 psi | 90% | 2953 fps | 100% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 57,261 psi | 82% | 3009 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 98% | 61,409 psi | 88% | 2904 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 30"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 80% | 58,653 psi | 84% | 2697 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 55,376 psi | 80% | 2746 fps | 100% |
| Accurate 3100 | <<locked>> | 80% | 32,358 psi | 46% | 2411 fps | 98.4% |
| Accurate 4064 | <<locked>> | 80% | 55,695 psi | 80% | 2713 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 43,569 psi | 63% | 2644 fps | 100% |
| Accurate MAGPRO | 98 gr | 84% | 37,855 psi | 54% | 2628 fps | 95.4% |
| ADI APS 450 | <<locked>> | 80% | 58,856 psi | 85% | 2136 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 51,706 psi | 74% | 2707 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 36,448 psi | 52% | 2533 fps | 97.2% |
| ADI AR 2213 | <<locked>> | 82% | 34,693 psi | 50% | 2520 fps | 95.1% |
| ADI AR 2217 | <<locked>> | 92% | 35,607 psi | 51% | 2536 fps | 95.8% |
| ADI AR 2225 | <<locked>> | 88% | 28,152 psi | 40% | 2395 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 52,721 psi | 76% | 2726 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 56,246 psi | 81% | 2795 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 41,800 psi | 60% | 2651 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 48,066 psi | 69% | 2759 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 36,434 psi | 52% | 2530 fps | 97.2% |
| Alliant Reloder-22 | <<locked>> | 80% | 32,227 psi | 46% | 2474 fps | 96% |
| Alliant Reloder-23 | <<locked>> | 80% | 31,082 psi | 45% | 2444 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 27,195 psi | 39% | 2362 fps | 97.3% |
| Alliant Reloder-26 | <<locked>> | 80% | 33,547 psi | 48% | 2575 fps | 99.7% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 44,947 psi | 65% | 2664 fps | 95.1% |
| Bofors RP15 | <<locked>> | 82% | 32,140 psi | 46% | 2474 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 53,592 psi | 77% | 2740 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 31,981 psi | 46% | 2503 fps | 95.1% |
| Bofors RP5 | <<locked>> | 80% | 32,227 psi | 46% | 2474 fps | 96% |
| Bofors RP7 | <<locked>> | 80% | 46,543 psi | 67% | 2644 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 88% | 34,113 psi | 49% | 2503 fps | 95.8% |
| Hodgdon H380 | <<locked>> | 80% | 53,679 psi | 77% | 2762 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 45,266 psi | 65% | 2694 fps | 99.8% |
| Hodgdon H4350 | <<locked>> | 80% | 47,834 psi | 69% | 2703 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 82% | 36,985 psi | 53% | 2523 fps | 95.3% |
| Hodgdon H4831 SC | <<locked>> | 82% | 36,318 psi | 52% | 2510 fps | 95.1% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 39,407 psi | 57% | 2536 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 58,813 psi | 84% | 2835 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 84% | 30,182 psi | 43% | 2487 fps | 95.4% |
| Hodgdon Superformance | <<locked>> | 80% | 44,411 psi | 64% | 2720 fps | 99.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,688 psi | 40% | 1549 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 58,697 psi | 84% | 2792 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 54,389 psi | 78% | 2733 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 56,463 psi | 81% | 2772 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 42,090 psi | 60% | 2585 fps | 99.2% |
| IMR 4451 Enduron | <<locked>> | 80% | 47,906 psi | 69% | 2671 fps | 99.9% |
| IMR 4831 | <<locked>> | 80% | 41,510 psi | 60% | 2595 fps | 100% |
| IMR 4895 | <<locked>> | 80% | 57,711 psi | 83% | 2818 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 36,535 psi | 52% | 2477 fps | 95.3% |
| IMR 7828 SSC | <<locked>> | 84% | 35,636 psi | 51% | 2556 fps | 95.6% |
| IMR 8133 Enduron | <<locked>> | 98% | 34,461 psi | 50% | 2585 fps | 95.9% |
| Lovex S060 | <<locked>> | 80% | 58,856 psi | 85% | 2753 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 54,824 psi | 79% | 2723 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 45,571 psi | 65% | 2621 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 43,787 psi | 63% | 2615 fps | 99.7% |
| Lovex S071 | <<locked>> | 80% | 27,876 psi | 40% | 2300 fps | 96.9% |
| Norma 203B | <<locked>> | 80% | 55,593 psi | 80% | 2782 fps | 100% |
| Norma 204 | <<locked>> | 80% | 41,814 psi | 60% | 2621 fps | 98.3% |
| Norma 217 | <<locked>> | 92% | 28,340 psi | 41% | 2441 fps | 95.5% |
| Norma MRP | 91.6 gr | 80% | 33,634 psi | 48% | 2543 fps | 97.9% |
| Norma URP | <<locked>> | 80% | 42,801 psi | 61% | 2635 fps | 100% |
| Ramshot Big Game | <<locked>> | 80% | 56,449 psi | 81% | 2808 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 35,085 psi | 50% | 2556 fps | 95.9% |
| Ramshot Hunter | <<locked>> | 80% | 41,582 psi | 60% | 2631 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 82% | 29,022 psi | 42% | 2385 fps | 95.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,210 psi | 41% | 1585 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 53,388 psi | 77% | 2753 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 51,010 psi | 73% | 2799 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 43,395 psi | 62% | 2667 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 41,655 psi | 60% | 2687 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 82% | 27,224 psi | 39% | 2398 fps | 95% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 37,028 psi | 53% | 2657 fps | 95.3% |
| Rottweil R 902 | <<locked>> | 80% | 56,550 psi | 81% | 2726 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 50,488 psi | 73% | 2694 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 37,811 psi | 54% | 2510 fps | 96.4% |
| Rottweil R 905 | <<locked>> | 80% | 35,636 psi | 51% | 2513 fps | 97.2% |
| Rottweil R 907 | <<locked>> | 80% | 46,543 psi | 67% | 2644 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 80% | 45,571 psi | 65% | 2621 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 54,824 psi | 79% | 2723 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 43,787 psi | 63% | 2615 fps | 99.7% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 51,692 psi | 74% | 2749 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 50,850 psi | 73% | 2569 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 44,599 psi | 64% | 2572 fps | 99.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 35,302 psi | 51% | 2510 fps | 97.1% |
| Somchem S355 | <<locked>> | 80% | 50,488 psi | 73% | 2690 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 38,406 psi | 55% | 2497 fps | 95.7% |
| Somchem S365 | <<locked>> | 80% | 39,653 psi | 57% | 2592 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 36,230 psi | 52% | 2497 fps | 98.1% |
| Vihtavuori N135 | <<locked>> | 80% | 57,261 psi | 82% | 2677 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 57,145 psi | 82% | 2694 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 48,240 psi | 69% | 2615 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 44,280 psi | 64% | 2625 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 31,343 psi | 45% | 2379 fps | 96.1% |
| Vihtavuori N540 | <<locked>> | 80% | 55,347 psi | 80% | 2700 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 43,671 psi | 63% | 2635 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 34,751 psi | 50% | 2510 fps | 99.9% |
| Vihtavuori N560 | 93.9 gr | 82% | 36,390 psi | 52% | 2589 fps | 95.5% |
| Vihtavuori N565 | <<locked>> | 88% | 36,201 psi | 52% | 2579 fps | 95.8% |
| Vihtavuori N568 | <<locked>> | 94% | 38,566 psi | 55% | 2674 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 43,149 psi | 62% | 2585 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 45,397 psi | 65% | 2697 fps | 99.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 27,485 psi | 39% | 2467 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 32,996 psi | 47% | 2425 fps | 96.1% |
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 105 powders for 37XC loaded with the .375 | 300gr | NorthFork Bonded Core. Vihtavuori N560 delivers the highest muzzle velocity at 3,045 fps; across all powders the maximum-charge window runs from 1,732 fps to 3,045 fps. ADI AR 2217 gives the best case fill at 100 %, and 105 of the 105 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (480 MPa), the top charges use 53–90 %, 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. ADI AR 2217, ADI AR 2218, ADI AR 2225 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. Vihtavuori N560, Accurate MAGPRO, Norma MRP rank at the top here: for 37XC with the .375 | 300gr | NorthFork Bonded Core they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, ADI AR 2218, Alliant Reloder-33, IMR 7977 Enduron 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.