Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Nosler Partition 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, ReloadSwiss RS 76 and Vihtavuori N570.
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% | 56,724 psi | 89% | 2799 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 55,579 psi | 87% | 2907 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 54,215 psi | 85% | 2831 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 56,376 psi | 88% | 2904 fps | 100% |
| ADI AR 2217 | <<locked>> | 96% | 54,853 psi | 86% | 2877 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 55,071 psi | 86% | 2999 fps | 98.9% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 57,493 psi | 90% | 2956 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 57,435 psi | 90% | 2874 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 56,826 psi | 89% | 2897 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 54,940 psi | 86% | 2802 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 55,114 psi | 86% | 2877 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 55,390 psi | 87% | 2887 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 56,637 psi | 89% | 2979 fps | 98.9% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 52,083 psi | 82% | 2900 fps | 97.8% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 56,695 psi | 89% | 2864 fps | 98.9% |
| Bofors RP15 | <<locked>> | 90% | 56,014 psi | 88% | 2884 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 54,766 psi | 86% | 2894 fps | 100% |
| Bofors RP5 | <<locked>> | 88% | 56,826 psi | 89% | 2897 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 56,478 psi | 89% | 2900 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 55,419 psi | 87% | 2835 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 54,447 psi | 85% | 2822 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 54,679 psi | 86% | 2736 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 54,056 psi | 85% | 2963 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,753 psi | 59% | 1795 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 56,434 psi | 88% | 2799 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 57,203 psi | 90% | 2799 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 55,927 psi | 88% | 2815 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 88% | 54,694 psi | 86% | 2884 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 52,707 psi | 83% | 2881 fps | 99.9% |
| Lovex S071 | <<locked>> | 92% | 54,752 psi | 86% | 2772 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 53,722 psi | 84% | 2904 fps | 100% |
| Norma MRP | <<locked>> | 86% | 56,913 psi | 89% | 2910 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 55,941 psi | 88% | 2910 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 54,157 psi | 85% | 2835 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,682 psi | 61% | 1837 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 54,621 psi | 86% | 2949 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 53,998 psi | 85% | 2920 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 54,882 psi | 86% | 2802 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 86% | 57,348 psi | 90% | 2867 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 56,956 psi | 89% | 2864 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 56,173 psi | 88% | 2792 fps | 99.8% |
| Somchem S365 | <<locked>> | 82% | 56,608 psi | 89% | 2792 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 57,609 psi | 90% | 2835 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 57,522 psi | 90% | 2822 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 56,536 psi | 89% | 2851 fps | 97.5% |
| Vihtavuori N555 | <<locked>> | 86% | 56,840 psi | 89% | 2831 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 56,376 psi | 88% | 2920 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 92% | 57,159 psi | 90% | 2910 fps | 100% |
| Vihtavuori N568 | <<locked>> | 94% | 54,752 psi | 86% | 2923 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 96% | 55,970 psi | 88% | 2986 fps | 98.5% |
| Winchester StaBALL HD | <<locked>> | 88% | 54,824 psi | 86% | 2890 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 57,464 psi | 90% | 2835 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% | 43,453 psi | 68% | 2592 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 44,991 psi | 71% | 2726 fps | 98.2% |
| ADI AR 2209 | <<locked>> | 80% | 47,471 psi | 74% | 2720 fps | 99.8% |
| ADI AR 2213 | <<locked>> | 80% | 42,728 psi | 67% | 2667 fps | 98.6% |
| ADI AR 2217 | <<locked>> | 80% | 31,879 psi | 50% | 2418 fps | 95.4% |
| ADI AR 2218 | <<locked>> | 92% | 41,234 psi | 65% | 2720 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 29,240 psi | 46% | 2392 fps | 97.4% |
| Alliant Reloder-19 | <<locked>> | 80% | 47,398 psi | 74% | 2713 fps | 99.8% |
| Alliant Reloder-22 | <<locked>> | 80% | 43,482 psi | 68% | 2674 fps | 99.4% |
| Alliant Reloder-23 | <<locked>> | 80% | 42,250 psi | 66% | 2608 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 36,550 psi | 57% | 2559 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 47,761 psi | 75% | 2776 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 42,134 psi | 66% | 2717 fps | 95.6% |
| Alliant Reloder-50 | <<locked>> | 96% | 44,918 psi | 70% | 2769 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 41,278 psi | 65% | 2582 fps | 95.4% |
| Bofors RP15 | <<locked>> | 80% | 40,466 psi | 63% | 2612 fps | 98.9% |
| Bofors RP30 | <<locked>> | 80% | 34,084 psi | 53% | 2493 fps | 96.6% |
| Bofors RP5 | <<locked>> | 80% | 43,482 psi | 68% | 2674 fps | 99.4% |
| Hodgdon H1000 | <<locked>> | 80% | 34,621 psi | 54% | 2490 fps | 97.2% |
| Hodgdon H4831 | <<locked>> | 80% | 45,179 psi | 71% | 2661 fps | 98.5% |
| Hodgdon H4831 SC | <<locked>> | 80% | 44,512 psi | 70% | 2651 fps | 98.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 51,256 psi | 80% | 2690 fps | 100% |
| Hodgdon Retumbo | 91.7 gr | 80% | 35,708 psi | 56% | 2602 fps | 98.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,326 psi | 44% | 1604 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 53,113 psi | 83% | 2749 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 53,751 psi | 84% | 2753 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 46,282 psi | 73% | 2654 fps | 98.8% |
| IMR 7828 SSC | <<locked>> | 80% | 41,495 psi | 65% | 2654 fps | 98.4% |
| IMR 8133 Enduron | <<locked>> | 86% | 32,793 psi | 51% | 2484 fps | 95.9% |
| Lovex S071 | <<locked>> | 80% | 37,463 psi | 59% | 2477 fps | 99.7% |
| Norma 217 | <<locked>> | 80% | 26,890 psi | 42% | 2336 fps | 95.3% |
| Norma MRP | <<locked>> | 80% | 46,093 psi | 72% | 2740 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 41,466 psi | 65% | 2664 fps | 98.7% |
| Ramshot Magnum | <<locked>> | 80% | 37,333 psi | 59% | 2543 fps | 99% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,095 psi | 46% | 1644 fps | 100% |
| ReloadSwiss RS 76 | 98.1 gr | 80% | 34,867 psi | 55% | 2575 fps | 99.3% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 34,316 psi | 54% | 2533 fps | 95% |
| Rottweil R 904 | <<locked>> | 80% | 48,283 psi | 76% | 2694 fps | 99.4% |
| Rottweil R 905 | <<locked>> | 80% | 47,021 psi | 74% | 2703 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 46,688 psi | 73% | 2700 fps | 99.8% |
| Somchem S361 | <<locked>> | 80% | 49,124 psi | 77% | 2684 fps | 99.1% |
| Somchem S365 | <<locked>> | 80% | 53,084 psi | 83% | 2746 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 47,442 psi | 74% | 2677 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 41,466 psi | 65% | 2562 fps | 99.4% |
| Vihtavuori N170 | <<locked>> | 88% | 46,166 psi | 72% | 2674 fps | 95.1% |
| Vihtavuori N555 | <<locked>> | 80% | 46,862 psi | 73% | 2680 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 45,716 psi | 72% | 2736 fps | 98.8% |
| Vihtavuori N565 | <<locked>> | 80% | 38,029 psi | 60% | 2562 fps | 97.1% |
| Vihtavuori N568 | <<locked>> | 84% | 38,319 psi | 60% | 2612 fps | 95.9% |
| Vihtavuori N570 | 104.6 gr | 88% | 41,887 psi | 66% | 2723 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 80% | 40,379 psi | 63% | 2671 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 43,598 psi | 68% | 2612 fps | 99.4% |
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 60 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Nosler Partition. ADI AR 2218 delivers the highest muzzle velocity at 2,999 fps; across all powders the maximum-charge window runs from 1,795 fps to 2,999 fps. Accurate 8700 gives the best case fill at 100 %, and 60 of the 60 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 1:15.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, ADI AR 2218, ADI AR 2225 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, ReloadSwiss RS 76, Vihtavuori N570 rank at the top here: for .338-378 Weath. Mag. with the .338 | 250gr | Nosler Partition they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon US 869, Lovex D100, Ramshot LRT 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.