Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Woodleigh RN 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 Vihtavuori N570, Alliant Reloder-33 and Hodgdon Retumbo.
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>> | 86% | 54,621 psi | 86% | 2772 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 45,252 psi | 71% | 2730 fps | 96.1% |
| Accurate MAGPRO | <<locked>> | 86% | 57,290 psi | 90% | 2940 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 84% | 55,695 psi | 87% | 2858 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 54,201 psi | 85% | 2874 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 96% | 56,811 psi | 89% | 2910 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 57,072 psi | 89% | 3038 fps | 99.3% |
| ADI AR 2225 | <<locked>> | 98% | 55,579 psi | 87% | 2930 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 55,245 psi | 87% | 2844 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 54,737 psi | 86% | 2871 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 56,608 psi | 89% | 2828 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 56,869 psi | 89% | 2900 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 57,290 psi | 90% | 2917 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 54,752 psi | 86% | 2949 fps | 98.7% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 54,375 psi | 85% | 2940 fps | 98.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 54,636 psi | 86% | 2838 fps | 98.7% |
| Bofors RP15 | <<locked>> | 90% | 57,696 psi | 90% | 2913 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 56,637 psi | 89% | 2923 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 54,737 psi | 86% | 2871 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 54,418 psi | 85% | 2874 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 56,884 psi | 89% | 2864 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 55,927 psi | 88% | 2848 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 56,130 psi | 88% | 2759 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 56,144 psi | 88% | 2995 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,768 psi | 59% | 1804 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 57,174 psi | 90% | 2838 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 88% | 56,492 psi | 89% | 2913 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 55,680 psi | 87% | 2785 fps | 95.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 54,636 psi | 86% | 2913 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 56,318 psi | 88% | 2795 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 55,956 psi | 88% | 2936 fps | 100% |
| Norma MRP | <<locked>> | 84% | 54,723 psi | 86% | 2881 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 53,737 psi | 84% | 2877 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 56,115 psi | 88% | 2864 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,812 psi | 61% | 1850 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 56,942 psi | 89% | 2982 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 56,188 psi | 88% | 2953 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 84% | 56,101 psi | 88% | 2825 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 55,129 psi | 86% | 2838 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 47,355 psi | 74% | 2746 fps | 96.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 54,752 psi | 86% | 2835 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 57,435 psi | 90% | 2818 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 55,405 psi | 87% | 2805 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 55,332 psi | 87% | 2795 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 54,433 psi | 85% | 2822 fps | 97.3% |
| Vihtavuori N555 | <<locked>> | 84% | 54,824 psi | 86% | 2805 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 54,157 psi | 85% | 2887 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 55,158 psi | 86% | 2884 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 94% | 56,637 psi | 89% | 2953 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 94% | 53,969 psi | 85% | 2956 fps | 98.3% |
| Winchester StaBALL HD | <<locked>> | 88% | 56,971 psi | 89% | 2920 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 55,158 psi | 86% | 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% | 44,759 psi | 70% | 2618 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 42,061 psi | 66% | 2664 fps | 95% |
| Accurate MAGPRO | <<locked>> | 80% | 46,499 psi | 73% | 2756 fps | 98.6% |
| ADI AR 2209 | <<locked>> | 80% | 48,689 psi | 76% | 2746 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 43,990 psi | 69% | 2697 fps | 98.9% |
| ADI AR 2217 | <<locked>> | 80% | 32,779 psi | 51% | 2444 fps | 96% |
| ADI AR 2218 | <<locked>> | 92% | 42,612 psi | 67% | 2756 fps | 95.8% |
| ADI AR 2225 | <<locked>> | 80% | 30,182 psi | 47% | 2421 fps | 98% |
| Alliant Reloder-19 | <<locked>> | 80% | 48,660 psi | 76% | 2740 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 44,759 psi | 70% | 2700 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 43,526 psi | 68% | 2631 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 37,695 psi | 59% | 2582 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 49,458 psi | 78% | 2802 fps | 100% |
| Alliant Reloder-33 | 111.8 gr | 88% | 40,683 psi | 64% | 2687 fps | 95.2% |
| Alliant Reloder-50 | <<locked>> | 94% | 43,497 psi | 68% | 2740 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 42,221 psi | 66% | 2608 fps | 95.9% |
| Bofors RP15 | <<locked>> | 80% | 41,626 psi | 65% | 2638 fps | 99.2% |
| Bofors RP30 | <<locked>> | 80% | 35,302 psi | 55% | 2523 fps | 97.1% |
| Bofors RP5 | <<locked>> | 80% | 44,759 psi | 70% | 2700 fps | 99.7% |
| Hodgdon H1000 | <<locked>> | 80% | 35,708 psi | 56% | 2523 fps | 97.8% |
| Hodgdon H4831 | <<locked>> | 80% | 46,514 psi | 73% | 2694 fps | 98.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 45,730 psi | 72% | 2677 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 52,562 psi | 82% | 2710 fps | 100% |
| Hodgdon Retumbo | 94.2 gr | 80% | 36,912 psi | 58% | 2635 fps | 99.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,471 psi | 45% | 1617 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 47,311 psi | 74% | 2677 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 80% | 42,815 psi | 67% | 2680 fps | 98.7% |
| IMR 7977 Enduron | <<locked>> | 90% | 52,257 psi | 82% | 2733 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 84% | 31,749 psi | 50% | 2454 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 38,638 psi | 61% | 2503 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 27,876 psi | 44% | 2365 fps | 96% |
| Norma MRP | <<locked>> | 80% | 47,529 psi | 74% | 2769 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 42,989 psi | 67% | 2694 fps | 99.1% |
| Ramshot Magnum | <<locked>> | 80% | 38,638 psi | 61% | 2572 fps | 99.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,225 psi | 46% | 1657 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 36,187 psi | 57% | 2608 fps | 99.6% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 35,650 psi | 56% | 2566 fps | 95.7% |
| Rottweil R 904 | <<locked>> | 80% | 49,385 psi | 77% | 2717 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 48,240 psi | 76% | 2730 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 44,179 psi | 69% | 2684 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 47,906 psi | 75% | 2723 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 50,459 psi | 79% | 2710 fps | 99.3% |
| Somchem S385 | <<locked>> | 80% | 48,689 psi | 76% | 2703 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 42,656 psi | 67% | 2589 fps | 99.6% |
| Vihtavuori N170 | <<locked>> | 88% | 47,601 psi | 75% | 2707 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 48,167 psi | 75% | 2703 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 47,137 psi | 74% | 2766 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 80% | 39,334 psi | 62% | 2595 fps | 97.6% |
| Vihtavuori N568 | <<locked>> | 82% | 36,985 psi | 58% | 2582 fps | 95.5% |
| Vihtavuori N570 | 107.5 gr | 88% | 43,555 psi | 68% | 2759 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 42,134 psi | 66% | 2697 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 44,918 psi | 70% | 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 59 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Woodleigh RN SN. ADI AR 2218 delivers the highest muzzle velocity at 3,038 fps; across all powders the maximum-charge window runs from 1,804 fps to 3,038 fps. Accurate 8700 gives the best case fill at 100 %, and 59 of the 59 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 1:6.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, ADI AR 2218, 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, Alliant Reloder-33, Hodgdon Retumbo rank at the top here: for .338-378 Weath. Mag. with the .338 | 250gr | Woodleigh RN SN they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, Lovex D100 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.