Load Specifications
Load data in caliber .378 Weath. Mag. with .375 | 300gr | Impala RNFP bullet and 78 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Accurate MAGPRO, Alliant Reloder-26 and Accurate High Country.
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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Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 94% | 54,447 psi | 85% | 2713 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 56,043 psi | 88% | 2743 fps | 100% |
| Accurate High Country | <<locked>> | 92% | 55,085 psi | 86% | 2854 fps | 99.1% |
| Accurate MAGPRO | <<locked>> | 94% | 55,651 psi | 87% | 2851 fps | 98.3% |
| ADI AR 2208 | <<locked>> | 82% | 56,594 psi | 89% | 2690 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 55,680 psi | 87% | 2785 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 96% | 56,942 psi | 89% | 2844 fps | 99.1% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 48,124 psi | 75% | 2694 fps | 98% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 43,120 psi | 68% | 2671 fps | 99.5% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 55,985 psi | 88% | 2785 fps | 99.6% |
| Alliant Reloder-16 | <<locked>> | 88% | 55,796 psi | 87% | 2782 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 56,971 psi | 89% | 2799 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 55,317 psi | 87% | 2779 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 96% | 57,000 psi | 89% | 2844 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 96% | 54,447 psi | 85% | 2766 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 53,505 psi | 84% | 2822 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 54,549 psi | 85% | 2854 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 96% | 55,259 psi | 87% | 2746 fps | 96.2% |
| Bofors RP15 | <<locked>> | 98% | 56,014 psi | 88% | 2831 fps | 99.6% |
| Bofors RP30ᴾ | <<locked>> | 100% | 49,821 psi | 78% | 2769 fps | 98.7% |
| Bofors RP5 | <<locked>> | 96% | 57,000 psi | 89% | 2844 fps | 99.8% |
| Bofors RP7 | <<locked>> | 84% | 54,737 psi | 86% | 2684 fps | 99.8% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 52,692 psi | 83% | 2776 fps | 99.2% |
| Hodgdon H414 | <<locked>> | 86% | 57,000 psi | 89% | 2785 fps | 100% |
| Hodgdon H4350 | <<locked>> | 84% | 55,970 psi | 88% | 2740 fps | 99.7% |
| Hodgdon H4831 | <<locked>> | 94% | 57,058 psi | 89% | 2785 fps | 98.6% |
| Hodgdon H4831 SC | <<locked>> | 94% | 55,898 psi | 88% | 2769 fps | 98.5% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 56,362 psi | 88% | 2710 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 52,562 psi | 82% | 2887 fps | 99.9% |
| Hodgdon Superformance | <<locked>> | 86% | 57,130 psi | 90% | 2825 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,333 psi | 59% | 1683 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 55,709 psi | 87% | 2720 fps | 99.9% |
| IMR 4451 Enduron | <<locked>> | 84% | 55,753 psi | 87% | 2700 fps | 100% |
| IMR 4831 | <<locked>> | 88% | 55,956 psi | 88% | 2730 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 54,853 psi | 86% | 2717 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 96% | 54,752 psi | 86% | 2822 fps | 98.9% |
| Lovex S065 | <<locked>> | 86% | 56,782 psi | 89% | 2703 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 55,027 psi | 86% | 2703 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 55,492 psi | 87% | 2726 fps | 100% |
| Norma 204 | <<locked>> | 88% | 56,565 psi | 89% | 2772 fps | 99.5% |
| Norma 217ᴾ | <<locked>> | 100% | 39,073 psi | 61% | 2612 fps | 98.2% |
| Norma MRP | <<locked>> | 94% | 56,797 psi | 89% | 2871 fps | 100% |
| Norma URP | <<locked>> | 88% | 57,377 psi | 90% | 2766 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 55,317 psi | 87% | 2841 fps | 99.3% |
| Ramshot Hunter | <<locked>> | 88% | 56,043 psi | 88% | 2776 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 57,377 psi | 90% | 2835 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,218 psi | 60% | 1726 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 56,449 psi | 88% | 2785 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 55,477 psi | 87% | 2762 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 56,797 psi | 89% | 2835 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 52,910 psi | 83% | 2884 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 48,124 psi | 75% | 2779 fps | 97% |
| Rottweil R 903 | <<locked>> | 82% | 56,405 psi | 88% | 2687 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 57,029 psi | 89% | 2753 fps | 99.1% |
| Rottweil R 905 | <<locked>> | 92% | 54,911 psi | 86% | 2769 fps | 99.6% |
| Rottweil R 907 | <<locked>> | 84% | 54,737 psi | 86% | 2684 fps | 99.8% |
| Shooters World Long Rifle | <<locked>> | 86% | 56,782 psi | 89% | 2703 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 55,027 psi | 86% | 2703 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 57,043 psi | 89% | 2736 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 55,767 psi | 87% | 2556 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 56,057 psi | 88% | 2661 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 54,462 psi | 85% | 2762 fps | 99.5% |
| Somchem S355 | <<locked>> | 82% | 55,811 psi | 87% | 2677 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 55,158 psi | 86% | 2700 fps | 98.3% |
| Somchem S365 | <<locked>> | 90% | 57,580 psi | 90% | 2769 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 55,840 psi | 88% | 2746 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 84% | 56,826 psi | 89% | 2648 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 55,680 psi | 87% | 2710 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 54,969 psi | 86% | 2723 fps | 99.7% |
| Vihtavuori N550 | <<locked>> | 86% | 55,042 psi | 86% | 2720 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 57,493 psi | 90% | 2795 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 56,637 psi | 89% | 2864 fps | 98.8% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 56,507 psi | 89% | 2844 fps | 99% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 49,385 psi | 77% | 2782 fps | 96.7% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 54,766 psi | 86% | 2671 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 57,145 psi | 90% | 2789 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 98% | 54,897 psi | 86% | 2897 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 55,201 psi | 87% | 2736 fps | 99.5% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 35,375 psi | 55% | 2375 fps | 98.1% |
| Accurate 4350 | <<locked>> | 80% | 46,369 psi | 73% | 2595 fps | 100% |
| Accurate High Country | 88.9 gr | 80% | 37,188 psi | 58% | 2516 fps | 95% |
| Accurate MAGPRO | 97.4 gr | 86% | 42,830 psi | 67% | 2628 fps | 95.4% |
| ADI AR 2208 | <<locked>> | 80% | 53,330 psi | 84% | 2644 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 38,348 psi | 60% | 2474 fps | 96.4% |
| ADI AR 2213 | <<locked>> | 84% | 39,015 psi | 61% | 2513 fps | 95.1% |
| ADI AR 2217 | <<locked>> | 94% | 39,972 psi | 63% | 2533 fps | 95.7% |
| ADI AR 2225 | <<locked>> | 88% | 30,414 psi | 48% | 2349 fps | 95% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 38,740 psi | 61% | 2477 fps | 96.6% |
| Alliant Reloder-16 | <<locked>> | 80% | 43,729 psi | 69% | 2592 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 49,966 psi | 78% | 2700 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 38,435 psi | 60% | 2470 fps | 96.5% |
| Alliant Reloder-22 | <<locked>> | 80% | 34,519 psi | 54% | 2425 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 33,489 psi | 52% | 2398 fps | 99.9% |
| Alliant Reloder-25 | <<locked>> | 80% | 29,472 psi | 46% | 2316 fps | 96.7% |
| Alliant Reloder-26 | 91.6 gr | 80% | 36,172 psi | 57% | 2530 fps | 99.5% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 52,170 psi | 82% | 2697 fps | 95.5% |
| Bofors RP15 | <<locked>> | 82% | 34,447 psi | 54% | 2421 fps | 95.1% |
| Bofors RP30 | <<locked>> | 90% | 36,637 psi | 57% | 2510 fps | 95.2% |
| Bofors RP5 | <<locked>> | 80% | 34,519 psi | 54% | 2425 fps | 95.3% |
| Bofors RP7 | <<locked>> | 80% | 48,617 psi | 76% | 2585 fps | 99.3% |
| Hodgdon H1000 | <<locked>> | 90% | 38,435 psi | 60% | 2503 fps | 95.8% |
| Hodgdon H414 | <<locked>> | 80% | 47,224 psi | 74% | 2631 fps | 99.5% |
| Hodgdon H4350 | <<locked>> | 80% | 49,588 psi | 78% | 2638 fps | 99.1% |
| Hodgdon H4831 | <<locked>> | 84% | 41,466 psi | 65% | 2520 fps | 95.3% |
| Hodgdon H4831 SC | <<locked>> | 84% | 40,770 psi | 64% | 2503 fps | 95.1% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 41,568 psi | 65% | 2487 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 34,374 psi | 54% | 2493 fps | 95.7% |
| Hodgdon Superformance | <<locked>> | 80% | 46,398 psi | 73% | 2657 fps | 99.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,065 psi | 44% | 1503 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 43,932 psi | 69% | 2523 fps | 98.7% |
| IMR 4451 Enduron | <<locked>> | 80% | 49,603 psi | 78% | 2605 fps | 99.6% |
| IMR 4831 | <<locked>> | 80% | 43,976 psi | 69% | 2543 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 40,799 psi | 64% | 2467 fps | 95.3% |
| IMR 7828 SSC | <<locked>> | 86% | 40,045 psi | 63% | 2552 fps | 95.6% |
| Lovex S065 | <<locked>> | 80% | 47,834 psi | 75% | 2566 fps | 99.9% |
| Lovex S070 | <<locked>> | 80% | 46,195 psi | 72% | 2562 fps | 99.4% |
| Lovex S071 | <<locked>> | 80% | 30,995 psi | 49% | 2270 fps | 96.7% |
| Norma 204 | <<locked>> | 80% | 43,830 psi | 69% | 2562 fps | 97.7% |
| Norma 217 | <<locked>> | 94% | 32,808 psi | 51% | 2457 fps | 95.9% |
| Norma MRP | <<locked>> | 80% | 35,940 psi | 56% | 2490 fps | 97.4% |
| Norma URP | <<locked>> | 80% | 45,078 psi | 71% | 2579 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 37,275 psi | 58% | 2500 fps | 95% |
| Ramshot Hunter | <<locked>> | 80% | 43,714 psi | 69% | 2575 fps | 99.5% |
| Ramshot Magnum | <<locked>> | 84% | 33,533 psi | 53% | 2398 fps | 95.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,805 psi | 45% | 1542 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 52,852 psi | 83% | 2736 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 45,759 psi | 72% | 2612 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 43,642 psi | 68% | 2625 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 31,575 psi | 49% | 2418 fps | 95.5% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 41,989 psi | 66% | 2657 fps | 95.2% |
| Rottweil R 903 | <<locked>> | 80% | 53,127 psi | 83% | 2641 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 39,798 psi | 62% | 2454 fps | 95.6% |
| Rottweil R 905 | <<locked>> | 80% | 37,956 psi | 59% | 2461 fps | 96.6% |
| Rottweil R 907 | <<locked>> | 80% | 48,617 psi | 76% | 2585 fps | 99.3% |
| Shooters World Long Rifle | <<locked>> | 80% | 47,834 psi | 75% | 2566 fps | 99.9% |
| Shooters World SW4350 | <<locked>> | 80% | 46,195 psi | 72% | 2562 fps | 99.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 53,621 psi | 84% | 2690 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 52,634 psi | 82% | 2513 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 46,731 psi | 73% | 2516 fps | 99.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 37,608 psi | 59% | 2457 fps | 96.4% |
| Somchem S355 | <<locked>> | 80% | 52,779 psi | 83% | 2635 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 42,989 psi | 67% | 2493 fps | 95.7% |
| Somchem S365 | <<locked>> | 80% | 42,003 psi | 66% | 2539 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 38,696 psi | 61% | 2448 fps | 97.6% |
| Vihtavuori N150 | <<locked>> | 80% | 50,444 psi | 79% | 2562 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 46,340 psi | 73% | 2569 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 33,591 psi | 53% | 2329 fps | 95.5% |
| Vihtavuori N550 | <<locked>> | 80% | 45,934 psi | 72% | 2579 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 37,579 psi | 59% | 2467 fps | 99.8% |
| Vihtavuori N560 | <<locked>> | 84% | 41,104 psi | 64% | 2585 fps | 95.5% |
| Vihtavuori N565 | <<locked>> | 88% | 38,740 psi | 61% | 2526 fps | 95.1% |
| Vihtavuori N568 | <<locked>> | 96% | 43,526 psi | 68% | 2671 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 45,020 psi | 71% | 2530 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 47,355 psi | 74% | 2635 fps | 99.5% |
| Winchester StaBALL HD | <<locked>> | 80% | 30,095 psi | 47% | 2428 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 35,244 psi | 55% | 2375 fps | 95.4% |
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 78 powders for .378 Weath. Mag. loaded with the .375 | 300gr | Impala RNFP. Winchester StaBALL HD delivers the highest muzzle velocity at 2,897 fps; across all powders the maximum-charge window runs from 1,683 fps to 2,897 fps. ADI AR 2217 gives the best case fill at 100 %, and 78 of the 78 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 59–90 %, leaving at least 10 % headroom. The 300.0 gr projectile in 0.375" calls for a 1:16.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-25 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. Accurate MAGPRO, Alliant Reloder-26, Accurate High Country rank at the top here: for .378 Weath. Mag. with the .375 | 300gr | Impala RNFP 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.