Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Woodleigh PP SN bullet and 52 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, Vihtavuori N570 and Alliant Reloder-33.
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% | 57,682 psi | 90% | 2759 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 57,508 psi | 90% | 2936 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 55,027 psi | 86% | 2786 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 57,334 psi | 90% | 2858 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 96% | 55,912 psi | 88% | 2836 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 56,884 psi | 89% | 2952 fps | 98.6% |
| ADI AR 2225 | <<locked>> | 98% | 55,579 psi | 87% | 2859 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 54,810 psi | 86% | 2779 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 53,969 psi | 85% | 2796 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 55,956 psi | 88% | 2763 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 56,086 psi | 88% | 2831 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 56,434 psi | 88% | 2845 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 53,911 psi | 84% | 2866 fps | 97.9% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 53,548 psi | 84% | 2854 fps | 97.4% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 57,696 psi | 90% | 2821 fps | 98.6% |
| Bofors RP15 | <<locked>> | 90% | 57,101 psi | 89% | 2904 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 55,840 psi | 88% | 2848 fps | 99.9% |
| Bofors RP5 | <<locked>> | 86% | 53,969 psi | 85% | 2854 fps | 100% |
| Hodgdon H1000 | <<locked>> | 96% | 57,537 psi | 90% | 2917 fps | 100% |
| Hodgdon H4831 | <<locked>> | 90% | 56,318 psi | 88% | 2794 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 86% | 55,201 psi | 87% | 2777 fps | 99.5% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 55,434 psi | 87% | 2698 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 55,274 psi | 87% | 2982 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,783 psi | 61% | 1772 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 57,246 psi | 90% | 2815 fps | 100% |
| IMR 4831 | <<locked>> | 84% | 56,159 psi | 88% | 2734 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 56,623 psi | 89% | 2828 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 86% | 55,695 psi | 87% | 2841 fps | 99.8% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 55,390 psi | 87% | 2837 fps | 99.8% |
| Lovex S071 | <<locked>> | 92% | 55,724 psi | 87% | 2732 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 55,666 psi | 87% | 2859 fps | 100% |
| Norma MRP | <<locked>> | 84% | 54,085 psi | 85% | 2811 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 55,767 psi | 87% | 2847 fps | 99.9% |
| Ramshot Magnum | <<locked>> | 88% | 57,072 psi | 89% | 2819 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,175 psi | 61% | 1815 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 55,941 psi | 88% | 2904 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 55,332 psi | 87% | 2874 fps | 99.5% |
| Rottweil R 904 | <<locked>> | 84% | 55,666 psi | 87% | 2758 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 84% | 54,462 psi | 85% | 2769 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 54,085 psi | 85% | 2822 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 56,942 psi | 89% | 2752 fps | 99.6% |
| Somchem S365 | <<locked>> | 82% | 57,551 psi | 90% | 2754 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 54,795 psi | 86% | 2740 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 56,623 psi | 89% | 2756 fps | 100% |
| Vihtavuori N170 | <<locked>> | 98% | 55,361 psi | 87% | 2774 fps | 96.7% |
| Vihtavuori N555 | <<locked>> | 84% | 54,128 psi | 85% | 2737 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 54,346 psi | 85% | 2827 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 90% | 54,418 psi | 85% | 2809 fps | 99.6% |
| Vihtavuori N568 | <<locked>> | 94% | 55,927 psi | 88% | 2876 fps | 99.2% |
| Vihtavuori N570 | <<locked>> | 96% | 57,725 psi | 90% | 2939 fps | 98.3% |
| Winchester StaBALL HD | <<locked>> | 88% | 56,014 psi | 88% | 2848 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 55,535 psi | 87% | 2753 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% | 44,150 psi | 69% | 2551 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 43,497 psi | 68% | 2690 fps | 97.3% |
| ADI AR 2209 | <<locked>> | 80% | 48,182 psi | 76% | 2674 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 80% | 43,395 psi | 68% | 2621 fps | 98.2% |
| ADI AR 2217 | <<locked>> | 82% | 34,693 psi | 54% | 2430 fps | 95.8% |
| ADI AR 2218 | <<locked>> | 94% | 45,136 psi | 71% | 2740 fps | 95.6% |
| ADI AR 2225 | <<locked>> | 80% | 29,747 psi | 47% | 2342 fps | 96.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 48,066 psi | 75% | 2668 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 80% | 44,164 psi | 69% | 2626 fps | 99.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 42,975 psi | 67% | 2565 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 37,217 psi | 58% | 2510 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 80% | 48,791 psi | 76% | 2731 fps | 100% |
| Alliant Reloder-33 | 113 gr | 90% | 43,047 psi | 67% | 2667 fps | 95% |
| Alliant Reloder-50 | <<locked>> | 96% | 46,035 psi | 72% | 2719 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 44,614 psi | 70% | 2596 fps | 95.8% |
| Bofors RP15 | <<locked>> | 80% | 41,147 psi | 64% | 2628 fps | 99% |
| Bofors RP30 | <<locked>> | 80% | 34,751 psi | 54% | 2445 fps | 96% |
| Bofors RP5 | <<locked>> | 80% | 44,164 psi | 69% | 2690 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 80% | 33,272 psi | 52% | 2457 fps | 96.8% |
| Hodgdon H4831 | <<locked>> | 80% | 40,640 psi | 64% | 2515 fps | 96.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 45,150 psi | 71% | 2605 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 52,011 psi | 82% | 2650 fps | 100% |
| Hodgdon Retumbo | 93.1 gr | 80% | 36,361 psi | 57% | 2618 fps | 99% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,384 psi | 44% | 1584 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 53,766 psi | 84% | 2762 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 49,632 psi | 78% | 2640 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 46,891 psi | 73% | 2667 fps | 98.9% |
| IMR 7828 SSC | <<locked>> | 80% | 44,947 psi | 70% | 2660 fps | 98.6% |
| IMR 8133 Enduron | <<locked>> | 86% | 33,489 psi | 52% | 2435 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 38,159 psi | 60% | 2436 fps | 99.5% |
| Norma 217 | <<locked>> | 82% | 29,443 psi | 46% | 2343 fps | 95.7% |
| Norma MRP | <<locked>> | 80% | 46,920 psi | 74% | 2695 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 47,776 psi | 75% | 2719 fps | 99.3% |
| Ramshot Magnum | <<locked>> | 80% | 42,003 psi | 66% | 2577 fps | 99.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,138 psi | 46% | 1623 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 35,665 psi | 56% | 2528 fps | 99% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 37,913 psi | 59% | 2548 fps | 95.5% |
| Rottweil R 904 | <<locked>> | 80% | 48,907 psi | 77% | 2650 fps | 99.2% |
| Rottweil R 905 | <<locked>> | 80% | 47,718 psi | 75% | 2658 fps | 99.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 47,413 psi | 74% | 2713 fps | 99.8% |
| Somchem S361 | <<locked>> | 80% | 49,937 psi | 78% | 2642 fps | 98.9% |
| Somchem S365 | <<locked>> | 80% | 53,882 psi | 84% | 2705 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 48,109 psi | 75% | 2635 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 40,901 psi | 64% | 2496 fps | 99% |
| Vihtavuori N170 | <<locked>> | 94% | 48,733 psi | 76% | 2662 fps | 95.1% |
| Vihtavuori N555 | <<locked>> | 80% | 47,630 psi | 75% | 2638 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 44,338 psi | 69% | 2649 fps | 97.9% |
| Vihtavuori N565 | <<locked>> | 80% | 38,769 psi | 61% | 2516 fps | 96.6% |
| Vihtavuori N568 | <<locked>> | 84% | 39,146 psi | 61% | 2564 fps | 95.3% |
| Vihtavuori N570 | 109.9 gr | 90% | 46,499 psi | 73% | 2745 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 80% | 41,350 psi | 65% | 2623 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 48,385 psi | 76% | 2641 fps | 99.6% |
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 52 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Woodleigh PP SN. Hodgdon Retumbo delivers the highest muzzle velocity at 2,982 fps; across all powders the maximum-charge window runs from 1,772 fps to 2,982 fps. ADI AR 2218 gives the best case fill at 100 %, and 52 of the 52 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 61–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.338" calls for a 1:16.5 twist; slower twists will usually not stabilise this weight. ADI AR 2218, Alliant Reloder-50, Hodgdon TrailBoss 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. Hodgdon Retumbo, Vihtavuori N570, Alliant Reloder-33 rank at the top here: for .338-378 Weath. Mag. with the .338 | 250gr | Woodleigh PP SN 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.