Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Barnes TSX BT bullet and 62 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N570, Hodgdon Retumbo and ReloadSwiss RS 76.
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>> | 88% | 55,100 psi | 86% | 2772 fps | 100% |
| Accurate High Country | <<locked>> | 86% | 56,753 psi | 89% | 2930 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 57,638 psi | 90% | 2936 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 86% | 56,260 psi | 88% | 2858 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 54,549 psi | 85% | 2874 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 98% | 56,869 psi | 89% | 2907 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 53,098 psi | 83% | 2956 fps | 98.4% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 55,317 psi | 87% | 2923 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 56,608 psi | 89% | 2854 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 56,608 psi | 89% | 2854 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 56,724 psi | 89% | 2841 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 55,999 psi | 88% | 2851 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 55,013 psi | 86% | 2867 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 56,782 psi | 89% | 2825 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 56,942 psi | 89% | 2900 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 57,522 psi | 90% | 2917 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 54,520 psi | 85% | 2943 fps | 98.5% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 49,908 psi | 78% | 2861 fps | 97.2% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 55,230 psi | 87% | 2835 fps | 98.6% |
| Bofors RP15 | <<locked>> | 90% | 54,389 psi | 85% | 2858 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 56,550 psi | 89% | 2917 fps | 100% |
| Bofors RP5 | <<locked>> | 88% | 55,013 psi | 86% | 2867 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 54,607 psi | 86% | 2871 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 57,711 psi | 90% | 2864 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 88% | 56,521 psi | 89% | 2848 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 56,753 psi | 89% | 2759 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 55,898 psi | 88% | 2989 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,724 psi | 59% | 1785 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 55,129 psi | 86% | 2776 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 55,753 psi | 87% | 2776 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 54,462 psi | 85% | 2785 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 90% | 56,739 psi | 89% | 2913 fps | 100% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 50,749 psi | 80% | 2851 fps | 99.8% |
| Lovex S070 | <<locked>> | 82% | 57,305 psi | 90% | 2802 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 56,724 psi | 89% | 2795 fps | 100% |
| Norma 204 | <<locked>> | 82% | 56,304 psi | 88% | 2835 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 51,648 psi | 81% | 2871 fps | 100% |
| Norma MRP | <<locked>> | 86% | 55,071 psi | 86% | 2884 fps | 100% |
| Norma URP | <<locked>> | 82% | 57,276 psi | 90% | 2818 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 53,998 psi | 85% | 2877 fps | 100% |
| Ramshot Hunter | <<locked>> | 82% | 56,289 psi | 88% | 2831 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 56,376 psi | 88% | 2864 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,667 psi | 61% | 1827 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 56,710 psi | 89% | 2979 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 55,985 psi | 88% | 2946 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 86% | 56,956 psi | 89% | 2825 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 86% | 55,622 psi | 87% | 2838 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 57,305 psi | 90% | 2802 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 57,740 psi | 90% | 2756 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 55,230 psi | 87% | 2835 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 54,665 psi | 86% | 2766 fps | 99.6% |
| Somchem S365 | <<locked>> | 82% | 55,013 psi | 86% | 2772 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 56,028 psi | 88% | 2808 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 55,869 psi | 88% | 2795 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 54,853 psi | 86% | 2818 fps | 97% |
| Vihtavuori N555 | <<locked>> | 86% | 55,187 psi | 86% | 2805 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 54,563 psi | 86% | 2887 fps | 99.7% |
| Vihtavuori N565 | <<locked>> | 92% | 55,332 psi | 87% | 2881 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 96% | 56,652 psi | 89% | 2949 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 96% | 53,795 psi | 84% | 2949 fps | 98.1% |
| Winchester StaBALL HD | <<locked>> | 90% | 56,681 psi | 89% | 2917 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 55,782 psi | 87% | 2805 fps | 100% |
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% | 42,134 psi | 66% | 2566 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 46,180 psi | 72% | 2753 fps | 99.1% |
| Accurate MAGPRO | <<locked>> | 80% | 43,598 psi | 68% | 2694 fps | 97.7% |
| ADI AR 2209 | <<locked>> | 80% | 46,108 psi | 72% | 2690 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 80% | 41,437 psi | 65% | 2638 fps | 98.2% |
| ADI AR 2217 | <<locked>> | 82% | 33,011 psi | 52% | 2444 fps | 95.7% |
| ADI AR 2218 | <<locked>> | 94% | 42,714 psi | 67% | 2749 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 80% | 28,282 psi | 44% | 2359 fps | 96.8% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 46,485 psi | 73% | 2690 fps | 99.6% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 46,485 psi | 73% | 2690 fps | 99.6% |
| Alliant Reloder-16 | <<locked>> | 80% | 53,084 psi | 83% | 2789 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 46,050 psi | 72% | 2684 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 80% | 42,148 psi | 66% | 2644 fps | 99.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 40,959 psi | 64% | 2585 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 35,302 psi | 55% | 2530 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 80% | 46,122 psi | 72% | 2746 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 43,569 psi | 68% | 2746 fps | 96% |
| Alliant Reloder-50 | <<locked>> | 96% | 42,960 psi | 67% | 2730 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 42,989 psi | 67% | 2612 fps | 95.8% |
| Bofors RP15 | <<locked>> | 80% | 39,175 psi | 61% | 2582 fps | 98.5% |
| Bofors RP30 | <<locked>> | 80% | 32,851 psi | 51% | 2464 fps | 96% |
| Bofors RP5 | <<locked>> | 80% | 42,148 psi | 66% | 2644 fps | 99.2% |
| Hodgdon H1000 | <<locked>> | 80% | 33,576 psi | 53% | 2461 fps | 96.7% |
| Hodgdon H4831 | <<locked>> | 80% | 44,077 psi | 69% | 2638 fps | 98.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 43,279 psi | 68% | 2621 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 49,908 psi | 78% | 2667 fps | 100% |
| Hodgdon Retumbo | 89.2 gr | 80% | 34,534 psi | 54% | 2569 fps | 98.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,297 psi | 44% | 1594 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 51,764 psi | 81% | 2726 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 52,286 psi | 82% | 2730 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 45,107 psi | 71% | 2628 fps | 98.5% |
| IMR 7828 SSC | <<locked>> | 80% | 40,147 psi | 63% | 2621 fps | 97.9% |
| IMR 8133 Enduron | <<locked>> | 86% | 31,589 psi | 50% | 2451 fps | 95.2% |
| Lovex S070 | <<locked>> | 80% | 53,824 psi | 84% | 2753 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 36,405 psi | 57% | 2454 fps | 99.5% |
| Norma 204 | <<locked>> | 80% | 52,634 psi | 82% | 2782 fps | 100% |
| Norma 217 | <<locked>> | 82% | 27,659 psi | 43% | 2359 fps | 95.7% |
| Norma MRP | <<locked>> | 80% | 44,686 psi | 70% | 2713 fps | 100% |
| Norma URP | <<locked>> | 80% | 53,693 psi | 84% | 2766 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 40,103 psi | 63% | 2631 fps | 98.3% |
| Ramshot Hunter | <<locked>> | 80% | 52,678 psi | 83% | 2779 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 35,984 psi | 56% | 2513 fps | 98.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,066 psi | 46% | 1634 fps | 100% |
| ReloadSwiss RS 76 | 95.5 gr | 80% | 33,678 psi | 53% | 2546 fps | 98.9% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 35,491 psi | 56% | 2562 fps | 95.4% |
| Rottweil R 904 | <<locked>> | 80% | 47,094 psi | 74% | 2667 fps | 99.2% |
| Rottweil R 905 | <<locked>> | 80% | 45,643 psi | 72% | 2677 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 80% | 53,824 psi | 84% | 2753 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 54,244 psi | 85% | 2707 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 45,310 psi | 71% | 2671 fps | 99.6% |
| Somchem S361 | <<locked>> | 80% | 47,921 psi | 75% | 2654 fps | 98.8% |
| Somchem S365 | <<locked>> | 80% | 51,459 psi | 81% | 2723 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 46,137 psi | 72% | 2651 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 40,263 psi | 63% | 2536 fps | 99.2% |
| Vihtavuori N170 | <<locked>> | 90% | 47,848 psi | 75% | 2703 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 80% | 45,513 psi | 71% | 2657 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 44,425 psi | 70% | 2710 fps | 98.4% |
| Vihtavuori N565 | <<locked>> | 80% | 36,825 psi | 58% | 2536 fps | 96.6% |
| Vihtavuori N568 | <<locked>> | 84% | 36,912 psi | 58% | 2582 fps | 95.3% |
| Vihtavuori N570 | 104.1 gr | 90% | 43,308 psi | 68% | 2756 fps | 95.4% |
| Winchester StaBALL HD | <<locked>> | 80% | 38,754 psi | 61% | 2644 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 42,380 psi | 66% | 2585 fps | 99.2% |
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 62 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Barnes TSX BT. Hodgdon Retumbo delivers the highest muzzle velocity at 2,989 fps; across all powders the maximum-charge window runs from 1,785 fps to 2,989 fps. ADI AR 2218 gives the best case fill at 100 %, and 62 of the 62 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 250.0 gr projectile in 0.338" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. ADI AR 2218, ADI AR 2225, Alliant Reloder-50 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 N570, Hodgdon Retumbo, ReloadSwiss RS 76 rank at the top here: for .338-378 Weath. Mag. with the .338 | 250gr | Barnes TSX BT 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.