Load Specifications
Load data in caliber .378 Weath. Mag. with .375 | 300gr | Speer AGS TBSS bullet and 80 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Accurate High Country, Alliant Reloder-26 and Winchester StaBALL HD.
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% | 57,450 psi | 90% | 2789 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 55,332 psi | 87% | 2766 fps | 100% |
| Accurate High Country | <<locked>> | 92% | 55,129 psi | 86% | 2887 fps | 99.3% |
| Accurate MAGPRO | <<locked>> | 94% | 55,898 psi | 88% | 2887 fps | 98.6% |
| ADI AR 2208 | <<locked>> | 82% | 56,405 psi | 88% | 2720 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 55,970 psi | 88% | 2825 fps | 99.7% |
| ADI AR 2213 | <<locked>> | 96% | 57,377 psi | 90% | 2887 fps | 99.4% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 47,993 psi | 75% | 2730 fps | 98.4% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 42,670 psi | 67% | 2694 fps | 99.6% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 56,202 psi | 88% | 2822 fps | 99.8% |
| Alliant Power Pro Varmint | <<locked>> | 92% | 56,202 psi | 88% | 2822 fps | 99.8% |
| Alliant Reloder-16 | <<locked>> | 88% | 56,043 psi | 88% | 2815 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 57,406 psi | 90% | 2831 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 55,506 psi | 87% | 2815 fps | 99.7% |
| Alliant Reloder-22 | <<locked>> | 96% | 57,276 psi | 90% | 2881 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 96% | 54,650 psi | 86% | 2795 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 53,867 psi | 84% | 2858 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 54,940 psi | 86% | 2884 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 96% | 55,564 psi | 87% | 2792 fps | 96.9% |
| Bofors RP15 | <<locked>> | 98% | 56,246 psi | 88% | 2867 fps | 99.8% |
| Bofors RP30ᴾ | <<locked>> | 100% | 49,864 psi | 78% | 2802 fps | 99% |
| Bofors RP5 | <<locked>> | 96% | 57,276 psi | 90% | 2881 fps | 99.9% |
| Bofors RP7 | <<locked>> | 84% | 54,360 psi | 85% | 2717 fps | 99.9% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 52,852 psi | 83% | 2815 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 86% | 56,927 psi | 89% | 2818 fps | 100% |
| Hodgdon H4350 | <<locked>> | 84% | 56,159 psi | 88% | 2779 fps | 99.8% |
| Hodgdon H4831 | <<locked>> | 94% | 57,406 psi | 90% | 2825 fps | 99% |
| Hodgdon H4831 SC | <<locked>> | 94% | 56,231 psi | 88% | 2808 fps | 98.8% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 56,449 psi | 88% | 2740 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 52,750 psi | 83% | 2923 fps | 100% |
| Hodgdon Superformance | <<locked>> | 86% | 57,522 psi | 90% | 2861 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,057 psi | 58% | 1709 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 55,767 psi | 87% | 2753 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 84% | 55,767 psi | 87% | 2736 fps | 100% |
| IMR 4831 | <<locked>> | 88% | 55,608 psi | 87% | 2756 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 54,839 psi | 86% | 2753 fps | 98.7% |
| IMR 7828 SSC | <<locked>> | 96% | 55,201 psi | 87% | 2864 fps | 99.3% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 38,348 psi | 60% | 2602 fps | 96.1% |
| Lovex S065 | <<locked>> | 86% | 56,376 psi | 88% | 2733 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 54,447 psi | 85% | 2733 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 54,839 psi | 86% | 2753 fps | 100% |
| Norma 204 | <<locked>> | 88% | 56,710 psi | 89% | 2812 fps | 99.7% |
| Norma 217ᴾ | <<locked>> | 100% | 38,290 psi | 60% | 2628 fps | 98.3% |
| Norma MRP | <<locked>> | 94% | 57,203 psi | 90% | 2904 fps | 100% |
| Norma URP | <<locked>> | 88% | 57,392 psi | 90% | 2799 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 55,825 psi | 87% | 2884 fps | 99.5% |
| Ramshot Hunter | <<locked>> | 88% | 56,115 psi | 88% | 2808 fps | 100% |
| Ramshot Magnum | <<locked>> | 98% | 53,896 psi | 84% | 2818 fps | 99.9% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,956 psi | 59% | 1752 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 82% | 56,898 psi | 89% | 2815 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 55,158 psi | 86% | 2789 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 57,232 psi | 90% | 2871 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 53,229 psi | 83% | 2923 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 48,124 psi | 75% | 2812 fps | 97.5% |
| Rottweil R 903 | <<locked>> | 82% | 55,492 psi | 87% | 2710 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 57,261 psi | 90% | 2792 fps | 99.3% |
| Rottweil R 905 | <<locked>> | 92% | 54,998 psi | 86% | 2802 fps | 99.7% |
| Rottweil R 907 | <<locked>> | 84% | 54,360 psi | 85% | 2717 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 86% | 56,376 psi | 88% | 2733 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 54,447 psi | 85% | 2733 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 57,058 psi | 89% | 2769 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 55,492 psi | 87% | 2585 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 55,608 psi | 87% | 2690 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 54,563 psi | 86% | 2799 fps | 99.7% |
| Somchem S355 | <<locked>> | 82% | 55,201 psi | 87% | 2703 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 55,071 psi | 86% | 2733 fps | 98.6% |
| Somchem S365 | <<locked>> | 88% | 53,998 psi | 85% | 2749 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 55,448 psi | 87% | 2776 fps | 100% |
| Vihtavuori N150 | <<locked>> | 84% | 56,463 psi | 88% | 2677 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 55,564 psi | 87% | 2740 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 54,926 psi | 86% | 2756 fps | 99.9% |
| Vihtavuori N550 | <<locked>> | 86% | 54,708 psi | 86% | 2746 fps | 100% |
| Vihtavuori N555 | <<locked>> | 94% | 57,145 psi | 90% | 2822 fps | 100% |
| Vihtavuori N560 | <<locked>> | 94% | 57,043 psi | 89% | 2900 fps | 99.2% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 56,594 psi | 89% | 2877 fps | 99.2% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 49,530 psi | 78% | 2818 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 54,940 psi | 86% | 2700 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 57,130 psi | 90% | 2822 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 98% | 55,898 psi | 88% | 2930 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 55,390 psi | 87% | 2772 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% | 33,663 psi | 53% | 2375 fps | 97.9% |
| Accurate 4350 | <<locked>> | 80% | 45,150 psi | 71% | 2612 fps | 100% |
| Accurate High Country | 94.4 gr | 80% | 36,260 psi | 57% | 2526 fps | 95% |
| Accurate MAGPRO | <<locked>> | 86% | 42,264 psi | 66% | 2648 fps | 95.6% |
| ADI AR 2208 | <<locked>> | 80% | 53,040 psi | 83% | 2674 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 37,681 psi | 59% | 2493 fps | 96.6% |
| ADI AR 2213 | <<locked>> | 84% | 38,450 psi | 60% | 2539 fps | 95.4% |
| ADI AR 2217 | <<locked>> | 92% | 36,883 psi | 58% | 2503 fps | 95% |
| ADI AR 2225 | <<locked>> | 90% | 31,067 psi | 49% | 2411 fps | 96% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 38,029 psi | 60% | 2497 fps | 96.7% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 38,029 psi | 60% | 2497 fps | 96.7% |
| Alliant Reloder-16 | <<locked>> | 80% | 43,221 psi | 68% | 2615 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 49,821 psi | 78% | 2726 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 37,681 psi | 59% | 2490 fps | 96.7% |
| Alliant Reloder-22 | <<locked>> | 80% | 33,562 psi | 53% | 2434 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 32,271 psi | 51% | 2402 fps | 99.8% |
| Alliant Reloder-25 | <<locked>> | 80% | 28,181 psi | 44% | 2316 fps | 96.5% |
| Alliant Reloder-26 | 97.3 gr | 80% | 35,143 psi | 55% | 2536 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 49,110 psi | 77% | 2684 fps | 95.3% |
| Bofors RP15 | <<locked>> | 82% | 33,344 psi | 52% | 2428 fps | 95% |
| Bofors RP30 | <<locked>> | 90% | 35,621 psi | 56% | 2520 fps | 95.3% |
| Bofors RP5 | <<locked>> | 80% | 33,562 psi | 53% | 2434 fps | 95.3% |
| Bofors RP7 | <<locked>> | 80% | 47,906 psi | 75% | 2612 fps | 99.4% |
| Hodgdon H1000 | <<locked>> | 88% | 35,288 psi | 55% | 2467 fps | 95.1% |
| Hodgdon H414 | <<locked>> | 80% | 46,818 psi | 73% | 2661 fps | 99.6% |
| Hodgdon H4350 | <<locked>> | 80% | 49,414 psi | 77% | 2671 fps | 99.3% |
| Hodgdon H4831 | <<locked>> | 84% | 41,031 psi | 64% | 2546 fps | 95.6% |
| Hodgdon H4831 SC | <<locked>> | 84% | 40,306 psi | 63% | 2530 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 40,785 psi | 64% | 2503 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 33,373 psi | 52% | 2503 fps | 95.7% |
| Hodgdon Superformance | <<locked>> | 80% | 46,093 psi | 72% | 2684 fps | 99.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,789 psi | 44% | 1526 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 43,395 psi | 68% | 2549 fps | 98.9% |
| IMR 4451 Enduron | <<locked>> | 80% | 49,269 psi | 77% | 2638 fps | 99.7% |
| IMR 4831 | <<locked>> | 80% | 42,960 psi | 67% | 2559 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 40,205 psi | 63% | 2493 fps | 95.6% |
| IMR 7828 SSC | <<locked>> | 86% | 39,436 psi | 62% | 2575 fps | 95.9% |
| IMR 8133 Enduron | <<locked>> | 98% | 35,868 psi | 56% | 2543 fps | 95.1% |
| Lovex S065 | <<locked>> | 80% | 46,847 psi | 73% | 2589 fps | 99.9% |
| Lovex S070 | <<locked>> | 80% | 45,165 psi | 71% | 2582 fps | 99.5% |
| Lovex S071 | <<locked>> | 80% | 29,037 psi | 46% | 2260 fps | 96.2% |
| Norma 204 | <<locked>> | 80% | 43,279 psi | 68% | 2585 fps | 97.9% |
| Norma 217 | <<locked>> | 94% | 31,502 psi | 49% | 2454 fps | 95.7% |
| Norma MRP | <<locked>> | 80% | 34,969 psi | 55% | 2500 fps | 97.4% |
| Norma URP | <<locked>> | 80% | 44,309 psi | 69% | 2598 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 36,405 psi | 57% | 2520 fps | 95.2% |
| Ramshot Hunter | <<locked>> | 80% | 43,033 psi | 67% | 2595 fps | 99.6% |
| Ramshot Magnum | <<locked>> | 84% | 32,430 psi | 51% | 2408 fps | 95.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,427 psi | 45% | 1565 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 52,895 psi | 83% | 2762 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 44,947 psi | 70% | 2631 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 43,192 psi | 68% | 2648 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 30,313 psi | 48% | 2418 fps | 95.4% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 41,495 psi | 65% | 2684 fps | 95.6% |
| Rottweil R 903 | <<locked>> | 80% | 52,112 psi | 82% | 2664 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 39,073 psi | 61% | 2474 fps | 95.8% |
| Rottweil R 905 | <<locked>> | 80% | 36,970 psi | 58% | 2477 fps | 96.6% |
| Rottweil R 907 | <<locked>> | 80% | 47,906 psi | 75% | 2612 fps | 99.4% |
| Shooters World Long Rifle | <<locked>> | 80% | 46,847 psi | 73% | 2589 fps | 99.9% |
| Shooters World SW4350 | <<locked>> | 80% | 45,165 psi | 71% | 2582 fps | 99.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 53,359 psi | 84% | 2717 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 52,272 psi | 82% | 2543 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 45,876 psi | 72% | 2539 fps | 99.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 36,651 psi | 57% | 2470 fps | 96.5% |
| Somchem S355 | <<locked>> | 80% | 51,938 psi | 81% | 2657 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 39,653 psi | 62% | 2464 fps | 95.1% |
| Somchem S365 | <<locked>> | 80% | 41,249 psi | 65% | 2556 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 37,608 psi | 59% | 2461 fps | 97.6% |
| Vihtavuori N150 | <<locked>> | 80% | 49,719 psi | 78% | 2585 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 45,730 psi | 72% | 2592 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 32,532 psi | 51% | 2339 fps | 95.5% |
| Vihtavuori N550 | <<locked>> | 80% | 45,121 psi | 71% | 2598 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 36,201 psi | 57% | 2474 fps | 99.8% |
| Vihtavuori N560 | <<locked>> | 84% | 40,495 psi | 63% | 2608 fps | 95.8% |
| Vihtavuori N565 | <<locked>> | 88% | 37,797 psi | 59% | 2539 fps | 95.2% |
| Vihtavuori N568 | <<locked>> | 96% | 42,989 psi | 67% | 2694 fps | 95.4% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 44,730 psi | 70% | 2556 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 46,949 psi | 74% | 2664 fps | 99.6% |
| Winchester StaBALL HD | 93.4 gr | 80% | 28,587 psi | 45% | 2421 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 34,258 psi | 54% | 2388 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 80 powders for .378 Weath. Mag. loaded with the .375 | 300gr | Speer AGS TBSS. Winchester StaBALL HD delivers the highest muzzle velocity at 2,930 fps; across all powders the maximum-charge window runs from 1,709 fps to 2,930 fps. ADI AR 2217 gives the best case fill at 100 %, and 80 of the 80 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 58–90 %, 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. Accurate High Country, Alliant Reloder-26, Winchester StaBALL HD rank at the top here: for .378 Weath. Mag. with the .375 | 300gr | Speer AGS TBSS 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.