Load Specifications
Load data in caliber .378 Weath. Mag. with .375 | 300gr | Sierra GameKing bullet and 83 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 3100 | <<locked>> | 96% | 55,448 psi | 87% | 2753 fps | 100% |
| Accurate 4350 | <<locked>> | 88% | 57,101 psi | 89% | 2782 fps | 100% |
| Accurate High Country | <<locked>> | 94% | 56,840 psi | 89% | 2907 fps | 99.4% |
| Accurate MAGPRO | <<locked>> | 94% | 53,824 psi | 84% | 2848 fps | 98.1% |
| ADI AR 2208 | <<locked>> | 82% | 55,071 psi | 86% | 2694 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 54,186 psi | 85% | 2789 fps | 99.5% |
| ADI AR 2213 | <<locked>> | 96% | 55,506 psi | 87% | 2848 fps | 99.1% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 46,296 psi | 73% | 2690 fps | 97.8% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 41,118 psi | 64% | 2657 fps | 99.3% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 54,346 psi | 85% | 2785 fps | 99.5% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 54,346 psi | 85% | 2785 fps | 99.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 56,347 psi | 88% | 2717 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 88% | 54,302 psi | 85% | 2785 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 55,448 psi | 87% | 2802 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 57,217 psi | 90% | 2831 fps | 99.8% |
| Alliant Reloder-22 | <<locked>> | 96% | 55,288 psi | 87% | 2844 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 98% | 56,260 psi | 88% | 2812 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 51,837 psi | 81% | 2822 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 94% | 56,724 psi | 89% | 2907 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 98% | 57,537 psi | 90% | 2808 fps | 97% |
| Bofors RP15 | <<locked>> | 98% | 54,114 psi | 85% | 2828 fps | 99.6% |
| Bofors RP3 | <<locked>> | 82% | 57,305 psi | 90% | 2733 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 47,790 psi | 75% | 2762 fps | 98.5% |
| Bofors RP5 | <<locked>> | 96% | 55,288 psi | 87% | 2844 fps | 99.7% |
| Bofors RP7 | <<locked>> | 86% | 56,289 psi | 88% | 2733 fps | 99.9% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 51,082 psi | 80% | 2776 fps | 99.1% |
| Hodgdon H380 | <<locked>> | 82% | 57,392 psi | 90% | 2756 fps | 100% |
| Hodgdon H414 | <<locked>> | 86% | 55,230 psi | 87% | 2785 fps | 100% |
| Hodgdon H4350 | <<locked>> | 84% | 54,621 psi | 86% | 2746 fps | 99.7% |
| Hodgdon H4831 | <<locked>> | 94% | 55,477 psi | 87% | 2789 fps | 98.6% |
| Hodgdon H4831 SC | <<locked>> | 94% | 54,317 psi | 85% | 2769 fps | 98.4% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 54,621 psi | 86% | 2710 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 50,807 psi | 80% | 2884 fps | 99.9% |
| Hodgdon Superformance | <<locked>> | 86% | 55,477 psi | 87% | 2825 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,028 psi | 58% | 1696 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 57,653 psi | 90% | 2772 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 86% | 57,725 psi | 90% | 2756 fps | 100% |
| IMR 4831 | <<locked>> | 90% | 57,450 psi | 90% | 2776 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 56,782 psi | 89% | 2772 fps | 98.8% |
| IMR 7828 SSC | <<locked>> | 98% | 56,956 psi | 89% | 2881 fps | 99.3% |
| Lovex S065 | <<locked>> | 86% | 54,839 psi | 86% | 2703 fps | 100% |
| Lovex S070 | <<locked>> | 88% | 56,362 psi | 88% | 2753 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 52,794 psi | 83% | 2717 fps | 100% |
| Norma 204 | <<locked>> | 88% | 54,998 psi | 86% | 2779 fps | 99.5% |
| Norma 217ᴾ | <<locked>> | 100% | 36,666 psi | 57% | 2582 fps | 97.7% |
| Norma MRP | <<locked>> | 94% | 54,984 psi | 86% | 2864 fps | 100% |
| Norma URP | <<locked>> | 88% | 55,593 psi | 87% | 2769 fps | 100% |
| Ramshot Grand | <<locked>> | 98% | 57,609 psi | 90% | 2904 fps | 99.6% |
| Ramshot Hunter | <<locked>> | 88% | 54,360 psi | 85% | 2776 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 55,767 psi | 87% | 2838 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,797 psi | 59% | 1736 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 57,101 psi | 89% | 2743 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 54,955 psi | 86% | 2785 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 57,159 psi | 90% | 2808 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 55,216 psi | 87% | 2838 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 51,039 psi | 80% | 2881 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 46,021 psi | 72% | 2766 fps | 96.8% |
| Rottweil R 903 | <<locked>> | 84% | 57,493 psi | 90% | 2730 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 55,593 psi | 87% | 2759 fps | 99% |
| Rottweil R 905 | <<locked>> | 94% | 56,695 psi | 89% | 2818 fps | 99.8% |
| Rottweil R 907 | <<locked>> | 86% | 56,289 psi | 88% | 2733 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 86% | 54,839 psi | 86% | 2703 fps | 100% |
| Shooters World SW4350 | <<locked>> | 88% | 56,362 psi | 88% | 2753 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 55,419 psi | 87% | 2740 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 57,537 psi | 90% | 2602 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 57,580 psi | 90% | 2710 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 56,231 psi | 88% | 2815 fps | 99.8% |
| Somchem S355 | <<locked>> | 84% | 57,130 psi | 90% | 2723 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 57,130 psi | 90% | 2753 fps | 98.7% |
| Somchem S365 | <<locked>> | 90% | 55,724 psi | 87% | 2769 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 57,188 psi | 90% | 2792 fps | 100% |
| Vihtavuori N150 | <<locked>> | 84% | 54,839 psi | 86% | 2651 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 57,435 psi | 90% | 2756 fps | 100% |
| Vihtavuori N165 | <<locked>> | 98% | 56,681 psi | 89% | 2772 fps | 99.9% |
| Vihtavuori N550 | <<locked>> | 88% | 56,507 psi | 89% | 2766 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 55,042 psi | 86% | 2789 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 54,897 psi | 86% | 2861 fps | 98.8% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 54,433 psi | 85% | 2841 fps | 98.9% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 47,471 psi | 74% | 2776 fps | 96.5% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 56,956 psi | 89% | 2720 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 55,376 psi | 87% | 2789 fps | 100% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 57,377 psi | 90% | 2946 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 57,290 psi | 90% | 2789 fps | 99.7% |
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% | 32,474 psi | 51% | 2343 fps | 97.4% |
| Accurate 4350 | <<locked>> | 80% | 43,714 psi | 69% | 2582 fps | 100% |
| Accurate High Country | <<locked>> | 82% | 37,550 psi | 59% | 2552 fps | 95.4% |
| Accurate MAGPRO | 102.6 gr | 88% | 43,584 psi | 68% | 2667 fps | 95.9% |
| ADI AR 2208 | <<locked>> | 80% | 51,851 psi | 81% | 2648 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 36,579 psi | 57% | 2461 fps | 96% |
| ADI AR 2213 | <<locked>> | 86% | 39,755 psi | 62% | 2562 fps | 95.7% |
| ADI AR 2217 | <<locked>> | 94% | 38,087 psi | 60% | 2520 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 90% | 30,037 psi | 47% | 2372 fps | 95.1% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 36,869 psi | 58% | 2464 fps | 96.2% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 36,869 psi | 58% | 2464 fps | 96.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 52,881 psi | 83% | 2667 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 41,959 psi | 66% | 2585 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 48,211 psi | 76% | 2697 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 36,550 psi | 57% | 2457 fps | 96.1% |
| Alliant Reloder-22 | <<locked>> | 82% | 34,563 psi | 54% | 2454 fps | 95.5% |
| Alliant Reloder-23 | <<locked>> | 80% | 31,198 psi | 49% | 2372 fps | 99.7% |
| Alliant Reloder-25 | <<locked>> | 80% | 27,296 psi | 43% | 2283 fps | 95.7% |
| Alliant Reloder-26 | <<locked>> | 80% | 33,649 psi | 53% | 2497 fps | 99.1% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 50,821 psi | 80% | 2700 fps | 95.5% |
| Bofors RP15 | <<locked>> | 84% | 34,345 psi | 54% | 2451 fps | 95.3% |
| Bofors RP3 | <<locked>> | 80% | 53,679 psi | 84% | 2684 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 36,535 psi | 57% | 2536 fps | 95.5% |
| Bofors RP5 | <<locked>> | 82% | 34,563 psi | 54% | 2454 fps | 95.5% |
| Bofors RP7 | <<locked>> | 80% | 46,673 psi | 73% | 2582 fps | 99.2% |
| Hodgdon H1000 | <<locked>> | 90% | 36,477 psi | 57% | 2487 fps | 95.4% |
| Hodgdon H380 | <<locked>> | 80% | 53,824 psi | 84% | 2703 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 45,397 psi | 71% | 2628 fps | 99.4% |
| Hodgdon H4350 | <<locked>> | 80% | 47,979 psi | 75% | 2638 fps | 99% |
| Hodgdon H4831 | <<locked>> | 84% | 39,726 psi | 62% | 2510 fps | 95% |
| Hodgdon H4831 SC | <<locked>> | 86% | 41,684 psi | 65% | 2549 fps | 95.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 39,508 psi | 62% | 2474 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 34,418 psi | 54% | 2526 fps | 96% |
| Hodgdon Superformance | <<locked>> | 80% | 44,527 psi | 70% | 2651 fps | 99.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,731 psi | 43% | 1516 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 42,221 psi | 66% | 2520 fps | 98.5% |
| IMR 4451 Enduron | <<locked>> | 80% | 48,037 psi | 75% | 2605 fps | 99.6% |
| IMR 4831 | <<locked>> | 80% | 41,655 psi | 65% | 2530 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 39,059 psi | 61% | 2461 fps | 95% |
| IMR 7828 SSC | <<locked>> | 86% | 38,174 psi | 60% | 2539 fps | 95.2% |
| Lovex S065 | <<locked>> | 80% | 45,716 psi | 72% | 2559 fps | 99.9% |
| Lovex S070 | <<locked>> | 80% | 43,918 psi | 69% | 2549 fps | 99.3% |
| Lovex S071 | <<locked>> | 80% | 28,007 psi | 44% | 2228 fps | 95.6% |
| Norma 204 | <<locked>> | 80% | 41,945 psi | 66% | 2552 fps | 97.5% |
| Norma 217 | <<locked>> | 96% | 32,227 psi | 51% | 2470 fps | 95.9% |
| Norma MRP | 91.6 gr | 80% | 33,721 psi | 53% | 2464 fps | 96.8% |
| Norma URP | <<locked>> | 80% | 42,946 psi | 67% | 2569 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 37,637 psi | 59% | 2539 fps | 95.4% |
| Ramshot Hunter | <<locked>> | 80% | 41,713 psi | 65% | 2566 fps | 99.4% |
| Ramshot Magnum | <<locked>> | 86% | 33,547 psi | 53% | 2428 fps | 96% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,253 psi | 44% | 1549 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 53,505 psi | 84% | 2690 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 51,169 psi | 80% | 2736 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 43,526 psi | 68% | 2602 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 41,771 psi | 65% | 2618 fps | 99.9% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 31,241 psi | 49% | 2438 fps | 95.7% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 42,714 psi | 67% | 2700 fps | 95.8% |
| Rottweil R 903 | <<locked>> | 80% | 50,647 psi | 79% | 2635 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 37,927 psi | 59% | 2441 fps | 95.2% |
| Rottweil R 905 | <<locked>> | 80% | 35,766 psi | 56% | 2441 fps | 96% |
| Rottweil R 907 | <<locked>> | 80% | 46,673 psi | 73% | 2582 fps | 99.2% |
| Shooters World Long Rifle | <<locked>> | 80% | 45,716 psi | 72% | 2559 fps | 99.9% |
| Shooters World SW4350 | <<locked>> | 80% | 43,918 psi | 69% | 2549 fps | 99.3% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 51,837 psi | 81% | 2690 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 50,995 psi | 80% | 2516 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 44,730 psi | 70% | 2510 fps | 99.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 35,447 psi | 56% | 2438 fps | 95.9% |
| Somchem S355 | <<locked>> | 80% | 50,633 psi | 79% | 2631 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 41,104 psi | 64% | 2487 fps | 95.4% |
| Somchem S365 | <<locked>> | 80% | 39,813 psi | 62% | 2530 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 36,332 psi | 57% | 2428 fps | 97.1% |
| Vihtavuori N150 | <<locked>> | 80% | 48,385 psi | 76% | 2559 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 44,425 psi | 70% | 2562 fps | 100% |
| Vihtavuori N165 | <<locked>> | 82% | 33,634 psi | 53% | 2362 fps | 95.7% |
| Vihtavuori N550 | <<locked>> | 80% | 43,801 psi | 69% | 2569 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 34,896 psi | 55% | 2441 fps | 99.6% |
| Vihtavuori N560 | 96.2 gr | 84% | 39,073 psi | 61% | 2572 fps | 95.1% |
| Vihtavuori N565 | <<locked>> | 90% | 38,769 psi | 61% | 2556 fps | 95.3% |
| Vihtavuori N568 | <<locked>> | 98% | 44,266 psi | 69% | 2713 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 43,265 psi | 68% | 2526 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 45,397 psi | 71% | 2628 fps | 99.4% |
| Winchester StaBALL HD | <<locked>> | 80% | 27,586 psi | 43% | 2382 fps | 99.8% |
| Winchester Supreme 780 | <<locked>> | 82% | 35,418 psi | 56% | 2408 fps | 95.7% |
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 83 powders for .378 Weath. Mag. loaded with the .375 | 300gr | Sierra GameKing. Winchester StaBALL HD delivers the highest muzzle velocity at 2,946 fps; across all powders the maximum-charge window runs from 1,696 fps to 2,946 fps. ADI AR 2217 gives the best case fill at 100 %, and 83 of the 83 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 57–90 %, 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 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. Vihtavuori N560, Norma MRP, Accurate MAGPRO rank at the top here: for .378 Weath. Mag. with the .375 | 300gr | Sierra GameKing 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.