Load Specifications
Load data in caliber .378 Weath. Mag. with .375 | 300gr | Atomic 29 HP bullet and 92 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N560, Norma MRP and Accurate MAGPRO.
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: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2700 | <<locked>> | 82% | 56,217 psi | 88% | 2687 fps | 99.8% |
| Accurate 3100 | <<locked>> | 98% | 54,984 psi | 86% | 2740 fps | 100% |
| Accurate 4064 | <<locked>> | 82% | 55,521 psi | 87% | 2651 fps | 100% |
| Accurate 4350 | <<locked>> | 90% | 57,145 psi | 90% | 2779 fps | 100% |
| Accurate High Country | <<locked>> | 96% | 56,637 psi | 89% | 2894 fps | 99.2% |
| Accurate MAGPRO | <<locked>> | 98% | 57,595 psi | 90% | 2897 fps | 98.5% |
| ADI AR 2208 | <<locked>> | 84% | 55,666 psi | 87% | 2694 fps | 100% |
| ADI AR 2209 | <<locked>> | 94% | 54,302 psi | 85% | 2782 fps | 99.4% |
| ADI AR 2213 | <<locked>> | 98% | 55,608 psi | 87% | 2838 fps | 98.9% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 43,250 psi | 68% | 2618 fps | 96.7% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 38,072 psi | 60% | 2579 fps | 98.4% |
| Alliant Power Pro Varmint | <<locked>> | 94% | 54,563 psi | 86% | 2779 fps | 99.4% |
| Alliant Power Pro Varmint | <<locked>> | 94% | 54,563 psi | 86% | 2779 fps | 99.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 56,724 psi | 89% | 2713 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 56,768 psi | 89% | 2736 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 54,447 psi | 85% | 2782 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 55,651 psi | 87% | 2799 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 96% | 57,435 psi | 90% | 2825 fps | 99.7% |
| Alliant Reloder-22 | <<locked>> | 98% | 54,984 psi | 86% | 2835 fps | 99.6% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 55,767 psi | 87% | 2799 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 48,095 psi | 75% | 2756 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 96% | 56,188 psi | 88% | 2897 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 98% | 54,534 psi | 85% | 2749 fps | 96% |
| Bofors RP15ᴾ | <<locked>> | 100% | 53,954 psi | 85% | 2818 fps | 99.5% |
| Bofors RP3 | <<locked>> | 84% | 57,595 psi | 90% | 2730 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 43,947 psi | 69% | 2687 fps | 97.5% |
| Bofors RP5 | <<locked>> | 98% | 54,984 psi | 86% | 2835 fps | 99.6% |
| Bofors RP7 | <<locked>> | 88% | 56,666 psi | 89% | 2730 fps | 99.9% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 47,572 psi | 75% | 2703 fps | 98.4% |
| Hodgdon H380 | <<locked>> | 82% | 54,157 psi | 85% | 2703 fps | 100% |
| Hodgdon H414 | <<locked>> | 88% | 55,521 psi | 87% | 2782 fps | 100% |
| Hodgdon H4350 | <<locked>> | 86% | 54,969 psi | 86% | 2743 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 96% | 55,883 psi | 88% | 2782 fps | 98.4% |
| Hodgdon H4831 SC | <<locked>> | 96% | 54,636 psi | 86% | 2766 fps | 98.2% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 54,679 psi | 86% | 2707 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 47,181 psi | 74% | 2808 fps | 99.4% |
| Hodgdon Superformance | <<locked>> | 88% | 55,724 psi | 87% | 2822 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,724 psi | 58% | 1677 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 55,187 psi | 86% | 2674 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 57,566 psi | 90% | 2717 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 54,505 psi | 85% | 2717 fps | 99.8% |
| IMR 4451 Enduron | <<locked>> | 86% | 55,027 psi | 86% | 2707 fps | 99.9% |
| IMR 4831 | <<locked>> | 92% | 57,392 psi | 90% | 2769 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 96% | 57,058 psi | 89% | 2766 fps | 98.7% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 57,014 psi | 89% | 2874 fps | 99.2% |
| Lovex S062 | <<locked>> | 82% | 55,405 psi | 87% | 2667 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 55,056 psi | 86% | 2700 fps | 100% |
| Lovex S070 | <<locked>> | 90% | 56,478 psi | 89% | 2746 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 48,892 psi | 77% | 2654 fps | 99.9% |
| Norma 203B | <<locked>> | 82% | 56,057 psi | 88% | 2720 fps | 100% |
| Norma 204 | <<locked>> | 90% | 55,419 psi | 87% | 2772 fps | 99.4% |
| Norma 217ᴾ | <<locked>> | 100% | 33,446 psi | 52% | 2500 fps | 96.1% |
| Norma MRP | <<locked>> | 96% | 54,708 psi | 86% | 2858 fps | 100% |
| Norma URP | <<locked>> | 90% | 55,651 psi | 87% | 2762 fps | 100% |
| Ramshot Big Game | <<locked>> | 82% | 57,188 psi | 90% | 2753 fps | 100% |
| Ramshot Grand | <<locked>> | 98% | 53,650 psi | 84% | 2831 fps | 99% |
| Ramshot Hunter | <<locked>> | 90% | 54,563 psi | 86% | 2772 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 51,590 psi | 81% | 2769 fps | 99.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,333 psi | 59% | 1716 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 57,682 psi | 90% | 2743 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 55,143 psi | 86% | 2785 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 57,087 psi | 89% | 2805 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 55,593 psi | 87% | 2838 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 47,137 psi | 74% | 2802 fps | 99.9% |
| Rottweil R 902 | <<locked>> | 82% | 57,101 psi | 89% | 2674 fps | 100% |
| Rottweil R 903 | <<locked>> | 84% | 54,143 psi | 85% | 2680 fps | 100% |
| Rottweil R 904 | <<locked>> | 94% | 55,956 psi | 88% | 2753 fps | 98.9% |
| Rottweil R 905 | <<locked>> | 96% | 56,724 psi | 89% | 2812 fps | 99.7% |
| Rottweil R 907 | <<locked>> | 88% | 56,666 psi | 89% | 2730 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 88% | 55,056 psi | 86% | 2700 fps | 100% |
| Shooters World Precision | <<locked>> | 82% | 55,405 psi | 87% | 2667 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 56,478 psi | 89% | 2746 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 55,738 psi | 87% | 2736 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 54,824 psi | 86% | 2559 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 54,592 psi | 86% | 2657 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 96% | 56,260 psi | 88% | 2808 fps | 99.7% |
| Somchem S355 | <<locked>> | 86% | 57,566 psi | 90% | 2723 fps | 100% |
| Somchem S361 | <<locked>> | 94% | 57,638 psi | 90% | 2749 fps | 98.6% |
| Somchem S365 | <<locked>> | 92% | 55,419 psi | 87% | 2762 fps | 100% |
| Somchem S385 | <<locked>> | 96% | 57,232 psi | 90% | 2782 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 86% | 55,347 psi | 87% | 2648 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 54,201 psi | 85% | 2707 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 56,652 psi | 89% | 2762 fps | 99.8% |
| Vihtavuori N540 | <<locked>> | 82% | 56,028 psi | 88% | 2644 fps | 100% |
| Vihtavuori N550 | <<locked>> | 90% | 56,695 psi | 89% | 2762 fps | 100% |
| Vihtavuori N555 | <<locked>> | 96% | 54,505 psi | 85% | 2776 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 54,853 psi | 86% | 2851 fps | 98.6% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 50,256 psi | 79% | 2766 fps | 98% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 57,435 psi | 90% | 2720 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 55,709 psi | 87% | 2785 fps | 100% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 52,185 psi | 82% | 2881 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 98% | 57,566 psi | 90% | 2785 fps | 99.6% |
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 2700 | <<locked>> | 80% | 52,620 psi | 82% | 2635 fps | 99.6% |
| Accurate 3100 | <<locked>> | 80% | 29,530 psi | 46% | 2270 fps | 96.1% |
| Accurate 4064 | <<locked>> | 80% | 52,185 psi | 82% | 2608 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 40,335 psi | 63% | 2516 fps | 99.8% |
| Accurate High Country | <<locked>> | 86% | 39,755 psi | 62% | 2598 fps | 95.9% |
| Accurate MAGPRO | 100.9 gr | 90% | 43,163 psi | 68% | 2654 fps | 95.4% |
| ADI AR 2208 | <<locked>> | 80% | 49,168 psi | 77% | 2598 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 36,550 psi | 57% | 2454 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 88% | 39,726 psi | 62% | 2552 fps | 95.3% |
| ADI AR 2217 | <<locked>> | 98% | 40,437 psi | 63% | 2562 fps | 95.7% |
| ADI AR 2225 | <<locked>> | 94% | 31,343 psi | 49% | 2405 fps | 95.5% |
| Alliant Power Pro Varmint | <<locked>> | 82% | 36,666 psi | 57% | 2454 fps | 95.8% |
| Alliant Power Pro Varmint | <<locked>> | 82% | 36,666 psi | 57% | 2454 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 49,908 psi | 78% | 2618 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 53,287 psi | 84% | 2687 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 39,189 psi | 61% | 2530 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 44,788 psi | 70% | 2641 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 36,318 psi | 57% | 2448 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 84% | 34,185 psi | 54% | 2444 fps | 95.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 28,660 psi | 45% | 2306 fps | 99% |
| Alliant Reloder-25 | <<locked>> | 82% | 26,818 psi | 42% | 2264 fps | 95.1% |
| Alliant Reloder-26 | <<locked>> | 80% | 30,719 psi | 48% | 2418 fps | 98% |
| Baschieri & Pellagri 109 | <<locked>> | 96% | 51,285 psi | 80% | 2694 fps | 95.2% |
| Bofors RP15 | <<locked>> | 88% | 36,187 psi | 57% | 2490 fps | 95.7% |
| Bofors RP3 | <<locked>> | 80% | 50,357 psi | 79% | 2631 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 38,392 psi | 60% | 2572 fps | 95.9% |
| Bofors RP5 | <<locked>> | 84% | 34,185 psi | 54% | 2444 fps | 95.1% |
| Bofors RP7 | <<locked>> | 80% | 44,106 psi | 69% | 2526 fps | 98.6% |
| Hodgdon H1000 | <<locked>> | 94% | 38,827 psi | 61% | 2530 fps | 95.9% |
| Hodgdon H380 | <<locked>> | 80% | 50,604 psi | 79% | 2651 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 42,395 psi | 66% | 2566 fps | 98.8% |
| Hodgdon H4350 | <<locked>> | 80% | 45,237 psi | 71% | 2582 fps | 98.4% |
| Hodgdon H4831 | <<locked>> | 88% | 42,482 psi | 67% | 2559 fps | 95.6% |
| Hodgdon H4831 SC | <<locked>> | 88% | 41,684 psi | 65% | 2543 fps | 95.3% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 36,782 psi | 58% | 2421 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 33,910 psi | 53% | 2503 fps | 95.4% |
| Hodgdon Superformance | <<locked>> | 80% | 41,408 psi | 65% | 2585 fps | 98.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,340 psi | 43% | 1496 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 51,706 psi | 81% | 2628 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 53,911 psi | 84% | 2664 fps | 99.9% |
| IMR 4350 | <<locked>> | 80% | 39,740 psi | 62% | 2464 fps | 97.8% |
| IMR 4451 Enduron | <<locked>> | 80% | 45,556 psi | 71% | 2556 fps | 99.2% |
| IMR 4831 | <<locked>> | 80% | 38,769 psi | 61% | 2470 fps | 99.7% |
| IMR 4955 Enduron | <<locked>> | 86% | 41,582 psi | 65% | 2503 fps | 95.5% |
| IMR 7828 SSC | <<locked>> | 90% | 40,625 psi | 64% | 2585 fps | 95.8% |
| Lovex S062 | <<locked>> | 80% | 51,938 psi | 81% | 2618 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 42,946 psi | 67% | 2503 fps | 99.5% |
| Lovex S070 | <<locked>> | 80% | 41,176 psi | 65% | 2493 fps | 98.7% |
| Lovex S071 | <<locked>> | 84% | 28,921 psi | 45% | 2254 fps | 95.8% |
| Norma 203B | <<locked>> | 80% | 52,605 psi | 82% | 2674 fps | 100% |
| Norma 204 | <<locked>> | 80% | 39,305 psi | 62% | 2493 fps | 96.5% |
| Norma 217 | <<locked>> | 98% | 31,299 psi | 49% | 2441 fps | 95% |
| Norma MRP | 88.1 gr | 80% | 31,009 psi | 49% | 2392 fps | 95.3% |
| Norma URP | <<locked>> | 80% | 40,103 psi | 63% | 2510 fps | 99.8% |
| Ramshot Big Game | <<locked>> | 80% | 53,345 psi | 84% | 2700 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 37,434 psi | 59% | 2530 fps | 95% |
| Ramshot Hunter | <<locked>> | 80% | 38,957 psi | 61% | 2507 fps | 98.8% |
| Ramshot Magnum | <<locked>> | 88% | 33,069 psi | 52% | 2411 fps | 95.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,934 psi | 44% | 1532 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 50,575 psi | 79% | 2638 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 47,616 psi | 75% | 2680 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 40,190 psi | 63% | 2536 fps | 99.7% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 38,841 psi | 61% | 2552 fps | 99.6% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 32,967 psi | 52% | 2484 fps | 96.3% |
| Rottweil R 902 | <<locked>> | 80% | 53,737 psi | 84% | 2628 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 47,442 psi | 74% | 2582 fps | 100% |
| Rottweil R 904 | <<locked>> | 84% | 40,538 psi | 64% | 2490 fps | 95.8% |
| Rottweil R 905 | <<locked>> | 82% | 35,491 psi | 56% | 2431 fps | 95.7% |
| Rottweil R 907 | <<locked>> | 80% | 44,106 psi | 69% | 2526 fps | 98.6% |
| Shooters World Long Rifle | <<locked>> | 80% | 42,946 psi | 67% | 2503 fps | 99.5% |
| Shooters World Precision | <<locked>> | 80% | 51,938 psi | 81% | 2618 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 41,176 psi | 65% | 2493 fps | 98.7% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 48,921 psi | 77% | 2641 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 48,399 psi | 76% | 2477 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 42,003 psi | 66% | 2454 fps | 98.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 35,157 psi | 55% | 2428 fps | 95.5% |
| Somchem S355 | <<locked>> | 80% | 47,645 psi | 75% | 2582 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 41,162 psi | 65% | 2477 fps | 95.1% |
| Somchem S365 | <<locked>> | 80% | 36,738 psi | 58% | 2470 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 33,591 psi | 53% | 2362 fps | 95.9% |
| Vihtavuori N150 | <<locked>> | 80% | 45,542 psi | 71% | 2510 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 41,495 psi | 65% | 2507 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 84% | 33,156 psi | 52% | 2346 fps | 95.3% |
| Vihtavuori N540 | <<locked>> | 80% | 52,460 psi | 82% | 2598 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 40,799 psi | 64% | 2510 fps | 99.7% |
| Vihtavuori N555 | <<locked>> | 80% | 31,952 psi | 50% | 2375 fps | 98.9% |
| Vihtavuori N560 | 96.9 gr | 88% | 41,539 psi | 65% | 2618 fps | 95.6% |
| Vihtavuori N565 | <<locked>> | 94% | 40,799 psi | 64% | 2595 fps | 95.8% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 40,466 psi | 63% | 2474 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 42,525 psi | 67% | 2569 fps | 98.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 25,222 psi | 40% | 2300 fps | 98.8% |
| Winchester Supreme 780 | <<locked>> | 84% | 35,244 psi | 55% | 2402 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 92 powders for .378 Weath. Mag. loaded with the .375 | 300gr | Atomic 29 HP. Accurate MAGPRO delivers the highest muzzle velocity at 2,897 fps; across all powders the maximum-charge window runs from 1,677 fps to 2,897 fps. ADI AR 2217 gives the best case fill at 100 %, and 92 of the 92 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 52–90 %, leaving at least 10 % headroom. The 300.0 gr projectile in 0.375" calls for a 1:16.0 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-23 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, Norma MRP, Accurate MAGPRO rank at the top here: for .378 Weath. Mag. with the .375 | 300gr | Atomic 29 HP 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.