Load Specifications
Load data in caliber .378 Weath. Mag. with .375 | 270gr | Swift A-Frame bullet and 85 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Norma MRP, Vihtavuori N560 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% | 56,710 psi | 89% | 2848 fps | 99.6% |
| Accurate 3100 | <<locked>> | 98% | 56,028 psi | 88% | 2907 fps | 100% |
| Accurate 4064 | <<locked>> | 82% | 56,478 psi | 89% | 2822 fps | 100% |
| Accurate 4350 | <<locked>> | 88% | 53,969 psi | 85% | 2890 fps | 100% |
| Accurate MAGPRO | <<locked>> | 96% | 54,259 psi | 85% | 2995 fps | 97.3% |
| ADI AR 2208 | <<locked>> | 84% | 56,028 psi | 88% | 2858 fps | 100% |
| ADI AR 2209 | <<locked>> | 94% | 54,911 psi | 86% | 2943 fps | 99.1% |
| ADI AR 2213 | <<locked>> | 98% | 56,231 psi | 88% | 3002 fps | 98.5% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 38,783 psi | 61% | 2723 fps | 97.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 57,261 psi | 90% | 2881 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 57,363 psi | 90% | 2904 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 54,882 psi | 86% | 2949 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 56,028 psi | 88% | 2966 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 54,273 psi | 85% | 2930 fps | 99% |
| Alliant Reloder-22 | <<locked>> | 98% | 55,709 psi | 87% | 2995 fps | 99.3% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 56,507 psi | 89% | 2966 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 48,805 psi | 76% | 2913 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 96% | 56,898 psi | 89% | 3064 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 54,505 psi | 85% | 2976 fps | 99.1% |
| Bofors RP3 | <<locked>> | 82% | 54,650 psi | 86% | 2848 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 44,701 psi | 70% | 2838 fps | 96.9% |
| Bofors RP5 | <<locked>> | 98% | 55,709 psi | 87% | 2995 fps | 99.3% |
| Bofors RP7 | <<locked>> | 88% | 57,276 psi | 90% | 2894 fps | 99.7% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 48,225 psi | 76% | 2854 fps | 97.8% |
| Hodgdon H380 | <<locked>> | 82% | 54,781 psi | 86% | 2867 fps | 100% |
| Hodgdon H414 | <<locked>> | 88% | 55,927 psi | 88% | 2946 fps | 99.9% |
| Hodgdon H4350 | <<locked>> | 86% | 55,347 psi | 87% | 2904 fps | 99.3% |
| Hodgdon H4831 | <<locked>> | 96% | 56,333 psi | 88% | 2940 fps | 97.9% |
| Hodgdon H4831 SC | <<locked>> | 96% | 55,187 psi | 86% | 2923 fps | 97.7% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 55,216 psi | 87% | 2871 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 47,776 psi | 75% | 2966 fps | 99% |
| Hodgdon Superformance | <<locked>> | 88% | 56,376 psi | 88% | 2986 fps | 99.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,738 psi | 58% | 1795 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 55,477 psi | 87% | 2838 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 55,085 psi | 86% | 2877 fps | 99.6% |
| IMR 4451 Enduron | <<locked>> | 86% | 55,288 psi | 87% | 2864 fps | 99.7% |
| IMR 4831 | <<locked>> | 90% | 54,404 psi | 85% | 2884 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 96% | 57,609 psi | 90% | 2923 fps | 98.2% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 57,508 psi | 90% | 3035 fps | 98.8% |
| Lovex S062 | <<locked>> | 82% | 55,840 psi | 88% | 2831 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 55,709 psi | 87% | 2864 fps | 100% |
| Lovex S070 | <<locked>> | 90% | 57,174 psi | 90% | 2910 fps | 99.9% |
| Lovex S071ᴾ | <<locked>> | 100% | 49,850 psi | 78% | 2815 fps | 99.8% |
| Norma 203B | <<locked>> | 82% | 56,710 psi | 89% | 2890 fps | 100% |
| Norma 204 | <<locked>> | 90% | 55,782 psi | 87% | 2933 fps | 99.1% |
| Norma MRP | <<locked>> | 96% | 55,332 psi | 87% | 3022 fps | 99.9% |
| Norma URP | <<locked>> | 90% | 56,246 psi | 88% | 2930 fps | 100% |
| Ramshot Big Game | <<locked>> | 82% | 57,566 psi | 90% | 2917 fps | 100% |
| Ramshot Grand | <<locked>> | 98% | 54,244 psi | 85% | 2992 fps | 98.6% |
| Ramshot Hunter | <<locked>> | 90% | 54,984 psi | 86% | 2933 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 52,257 psi | 82% | 2927 fps | 99.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,565 psi | 59% | 1837 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 54,534 psi | 85% | 2851 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 55,564 psi | 87% | 2956 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 53,954 psi | 85% | 2913 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 55,941 psi | 88% | 2999 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 47,950 psi | 75% | 2959 fps | 99.6% |
| Rottweil R 902 | <<locked>> | 82% | 57,682 psi | 90% | 2838 fps | 100% |
| Rottweil R 903 | <<locked>> | 84% | 54,839 psi | 86% | 2844 fps | 100% |
| Rottweil R 904 | <<locked>> | 94% | 56,333 psi | 88% | 2910 fps | 98.5% |
| Rottweil R 905 | <<locked>> | 96% | 57,392 psi | 90% | 2976 fps | 99.5% |
| Rottweil R 907 | <<locked>> | 88% | 57,276 psi | 90% | 2894 fps | 99.7% |
| Shooters World Long Rifle | <<locked>> | 88% | 55,709 psi | 87% | 2864 fps | 100% |
| Shooters World Precision | <<locked>> | 82% | 55,840 psi | 88% | 2831 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 57,174 psi | 90% | 2910 fps | 99.9% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 56,231 psi | 88% | 2904 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 55,303 psi | 87% | 2720 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 55,158 psi | 86% | 2818 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 96% | 56,927 psi | 89% | 2969 fps | 99.4% |
| Somchem S355 | <<locked>> | 84% | 54,694 psi | 86% | 2841 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 54,505 psi | 85% | 2851 fps | 97.5% |
| Somchem S365 | <<locked>> | 92% | 56,115 psi | 88% | 2930 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 54,273 psi | 85% | 2894 fps | 99.5% |
| Vihtavuori N150 | <<locked>> | 86% | 55,796 psi | 87% | 2812 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 54,563 psi | 86% | 2867 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 57,261 psi | 90% | 2923 fps | 99.6% |
| Vihtavuori N540 | <<locked>> | 82% | 56,579 psi | 89% | 2808 fps | 100% |
| Vihtavuori N550 | <<locked>> | 90% | 57,319 psi | 90% | 2927 fps | 100% |
| Vihtavuori N555 | <<locked>> | 96% | 55,390 psi | 87% | 2943 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 55,376 psi | 87% | 3012 fps | 98.1% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 51,082 psi | 80% | 2927 fps | 97.5% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 54,056 psi | 85% | 2831 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 56,231 psi | 88% | 2949 fps | 99.9% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 52,765 psi | 83% | 3048 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 54,259 psi | 85% | 2887 fps | 99% |
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% | 53,069 psi | 83% | 2789 fps | 99.3% |
| Accurate 3100 | <<locked>> | 80% | 30,443 psi | 48% | 2411 fps | 95.5% |
| Accurate 4064 | <<locked>> | 80% | 53,069 psi | 83% | 2772 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 41,162 psi | 65% | 2671 fps | 99.6% |
| Accurate MAGPRO | 110.6 gr | 92% | 47,079 psi | 74% | 2871 fps | 95.6% |
| ADI AR 2208 | <<locked>> | 80% | 49,530 psi | 78% | 2756 fps | 100% |
| ADI AR 2209 | <<locked>> | 84% | 39,508 psi | 62% | 2654 fps | 95.8% |
| ADI AR 2213 | <<locked>> | 90% | 42,946 psi | 67% | 2756 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 96% | 34,185 psi | 54% | 2602 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 50,459 psi | 79% | 2782 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 53,809 psi | 84% | 2851 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 39,610 psi | 62% | 2677 fps | 99.7% |
| Alliant Reloder-17 | <<locked>> | 80% | 45,324 psi | 71% | 2799 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 36,927 psi | 58% | 2592 fps | 95% |
| Alliant Reloder-22 | <<locked>> | 86% | 37,188 psi | 58% | 2644 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 29,298 psi | 46% | 2441 fps | 98.5% |
| Alliant Reloder-25 | <<locked>> | 84% | 29,240 psi | 46% | 2454 fps | 95.3% |
| Alliant Reloder-26 | <<locked>> | 80% | 31,560 psi | 49% | 2566 fps | 97.5% |
| Bofors RP15 | <<locked>> | 88% | 36,927 psi | 58% | 2635 fps | 95% |
| Bofors RP3 | <<locked>> | 80% | 51,140 psi | 80% | 2795 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 39,131 psi | 61% | 2720 fps | 95.1% |
| Bofors RP5 | <<locked>> | 86% | 37,188 psi | 58% | 2644 fps | 95.3% |
| Bofors RP7 | <<locked>> | 80% | 44,570 psi | 70% | 2677 fps | 98.1% |
| Hodgdon H1000 | <<locked>> | 94% | 39,450 psi | 62% | 2674 fps | 95.1% |
| Hodgdon H380 | <<locked>> | 80% | 51,329 psi | 80% | 2812 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 42,989 psi | 67% | 2720 fps | 98.4% |
| Hodgdon H4350 | <<locked>> | 80% | 45,759 psi | 72% | 2736 fps | 97.8% |
| Hodgdon H4831 | <<locked>> | 90% | 45,992 psi | 72% | 2762 fps | 95.7% |
| Hodgdon H4831 SC | <<locked>> | 90% | 45,063 psi | 71% | 2746 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 37,246 psi | 58% | 2566 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 92% | 36,840 psi | 58% | 2707 fps | 95.6% |
| Hodgdon Superformance | <<locked>> | 80% | 41,887 psi | 66% | 2733 fps | 97.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,514 psi | 43% | 1604 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 52,127 psi | 82% | 2789 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 40,161 psi | 63% | 2608 fps | 97.2% |
| IMR 4451 Enduron | <<locked>> | 80% | 45,963 psi | 72% | 2703 fps | 98.7% |
| IMR 4831 | <<locked>> | 80% | 39,349 psi | 62% | 2618 fps | 99.4% |
| IMR 4955 Enduron | <<locked>> | 88% | 44,875 psi | 70% | 2707 fps | 95.6% |
| IMR 7828 SSC | <<locked>> | 92% | 43,932 psi | 69% | 2789 fps | 95.9% |
| Lovex S062 | <<locked>> | 80% | 52,489 psi | 82% | 2782 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 43,511 psi | 68% | 2657 fps | 99.2% |
| Lovex S070 | <<locked>> | 80% | 41,800 psi | 66% | 2641 fps | 98.2% |
| Lovex S071 | <<locked>> | 84% | 29,892 psi | 47% | 2395 fps | 95.2% |
| Norma 203B | <<locked>> | 80% | 53,142 psi | 83% | 2838 fps | 100% |
| Norma 204 | <<locked>> | 80% | 39,755 psi | 62% | 2638 fps | 95.7% |
| Norma MRP | 96.8 gr | 82% | 33,968 psi | 53% | 2592 fps | 95.6% |
| Norma URP | <<locked>> | 80% | 40,640 psi | 64% | 2661 fps | 99.5% |
| Ramshot Big Game | <<locked>> | 80% | 53,824 psi | 84% | 2864 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 40,741 psi | 64% | 2733 fps | 95.2% |
| Ramshot Hunter | <<locked>> | 80% | 39,392 psi | 62% | 2651 fps | 98.3% |
| Ramshot Magnum | <<locked>> | 90% | 36,361 psi | 57% | 2615 fps | 95.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,079 psi | 44% | 1644 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 51,053 psi | 80% | 2795 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 48,095 psi | 75% | 2844 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 40,901 psi | 64% | 2690 fps | 99.5% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 39,436 psi | 62% | 2703 fps | 99.2% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 33,808 psi | 53% | 2625 fps | 95.4% |
| Rottweil R 902 | <<locked>> | 80% | 54,244 psi | 85% | 2792 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 48,124 psi | 75% | 2743 fps | 100% |
| Rottweil R 904 | <<locked>> | 84% | 41,046 psi | 64% | 2635 fps | 95% |
| Rottweil R 905 | <<locked>> | 84% | 38,537 psi | 60% | 2631 fps | 95.8% |
| Rottweil R 907 | <<locked>> | 80% | 44,570 psi | 70% | 2677 fps | 98.1% |
| Shooters World Long Rifle | <<locked>> | 80% | 43,511 psi | 68% | 2657 fps | 99.2% |
| Shooters World Precision | <<locked>> | 80% | 52,489 psi | 82% | 2782 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 41,800 psi | 66% | 2641 fps | 98.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 49,298 psi | 77% | 2799 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 48,892 psi | 77% | 2631 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 42,612 psi | 67% | 2602 fps | 98.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 38,189 psi | 60% | 2625 fps | 95.6% |
| Somchem S355 | <<locked>> | 80% | 48,196 psi | 76% | 2740 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 44,614 psi | 70% | 2677 fps | 95.2% |
| Somchem S365 | <<locked>> | 80% | 37,289 psi | 58% | 2618 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 34,360 psi | 54% | 2507 fps | 95.2% |
| Vihtavuori N150 | <<locked>> | 80% | 46,108 psi | 72% | 2667 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 42,047 psi | 66% | 2657 fps | 99.7% |
| Vihtavuori N165 | <<locked>> | 86% | 36,172 psi | 57% | 2543 fps | 95.5% |
| Vihtavuori N540 | <<locked>> | 80% | 53,113 psi | 83% | 2762 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 41,510 psi | 65% | 2661 fps | 99.5% |
| Vihtavuori N555 | <<locked>> | 80% | 32,677 psi | 51% | 2516 fps | 98.5% |
| Vihtavuori N560 | 106.2 gr | 90% | 45,049 psi | 71% | 2825 fps | 95.7% |
| Vihtavuori N565 | <<locked>> | 94% | 41,597 psi | 65% | 2746 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 41,075 psi | 64% | 2625 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 43,105 psi | 68% | 2723 fps | 98.4% |
| Winchester StaBALL HD | <<locked>> | 80% | 25,904 psi | 41% | 2434 fps | 98.2% |
| Winchester Supreme 780 | <<locked>> | 86% | 38,348 psi | 60% | 2595 fps | 95.5% |
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 85 powders for .378 Weath. Mag. loaded with the .375 | 270gr | Swift A-Frame. Alliant Reloder-26 delivers the highest muzzle velocity at 3,064 fps; across all powders the maximum-charge window runs from 1,795 fps to 3,064 fps. ADI AR 2225 gives the best case fill at 100 %, and 85 of the 85 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 270.0 gr projectile in 0.375" calls for a 1:6.0 twist; slower twists will usually not stabilise this weight. ADI AR 2225, Alliant Reloder-23, 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. Norma MRP, Vihtavuori N560, Accurate MAGPRO rank at the top here: for .378 Weath. Mag. with the .375 | 270gr | Swift A-Frame 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.