Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Hornady SP bullet and 57 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% | 56,550 psi | 89% | 2795 fps | 100% |
| Accurate High Country | <<locked>> | 84% | 54,563 psi | 86% | 2897 fps | 99.9% |
| Accurate MAGPRO | <<locked>> | 86% | 55,477 psi | 87% | 2907 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 54,056 psi | 85% | 2828 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 56,217 psi | 88% | 2900 fps | 100% |
| ADI AR 2217 | <<locked>> | 96% | 54,708 psi | 86% | 2877 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 54,969 psi | 86% | 2995 fps | 98.9% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 57,348 psi | 90% | 2953 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 84% | 54,447 psi | 85% | 2828 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 84% | 54,447 psi | 85% | 2828 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 57,319 psi | 90% | 2871 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 56,666 psi | 89% | 2894 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 54,766 psi | 86% | 2802 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 54,955 psi | 86% | 2874 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 55,216 psi | 87% | 2887 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 56,521 psi | 89% | 2976 fps | 98.9% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 51,967 psi | 81% | 2897 fps | 97.7% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 56,608 psi | 89% | 2861 fps | 98.9% |
| Bofors RP15 | <<locked>> | 90% | 56,014 psi | 88% | 2884 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 54,679 psi | 86% | 2890 fps | 100% |
| Bofors RP5 | <<locked>> | 88% | 56,666 psi | 89% | 2894 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 56,318 psi | 88% | 2897 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 55,259 psi | 87% | 2831 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 54,331 psi | 85% | 2818 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 54,520 psi | 85% | 2733 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 53,940 psi | 85% | 2959 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,710 psi | 59% | 1795 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 56,434 psi | 88% | 2802 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 57,203 psi | 90% | 2802 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 55,782 psi | 87% | 2812 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 88% | 54,563 psi | 86% | 2884 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 52,562 psi | 82% | 2881 fps | 99.9% |
| Lovex S071 | <<locked>> | 92% | 54,795 psi | 86% | 2772 fps | 100% |
| Norma 204 | <<locked>> | 82% | 57,667 psi | 90% | 2861 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 53,563 psi | 84% | 2900 fps | 100% |
| Norma MRP | <<locked>> | 86% | 56,797 psi | 89% | 2910 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 55,767 psi | 87% | 2904 fps | 100% |
| Ramshot Hunter | <<locked>> | 82% | 57,653 psi | 90% | 2851 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 54,172 psi | 85% | 2835 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,754 psi | 61% | 1837 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 54,476 psi | 85% | 2949 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 53,867 psi | 84% | 2917 fps | 99.6% |
| Rottweil R 904 | <<locked>> | 84% | 54,723 psi | 86% | 2799 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 86% | 57,188 psi | 90% | 2864 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 56,782 psi | 89% | 2861 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 56,043 psi | 88% | 2792 fps | 99.8% |
| Somchem S365 | <<locked>> | 82% | 56,579 psi | 89% | 2792 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 57,479 psi | 90% | 2831 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 57,392 psi | 90% | 2818 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 56,420 psi | 88% | 2848 fps | 97.5% |
| Vihtavuori N555 | <<locked>> | 86% | 56,710 psi | 89% | 2828 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 56,217 psi | 88% | 2917 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 92% | 57,029 psi | 89% | 2907 fps | 100% |
| Vihtavuori N568 | <<locked>> | 94% | 54,607 psi | 86% | 2920 fps | 99.4% |
| Vihtavuori N570 | <<locked>> | 96% | 55,825 psi | 87% | 2982 fps | 98.5% |
| Winchester StaBALL HD | <<locked>> | 88% | 54,636 psi | 86% | 2890 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 57,319 psi | 90% | 2831 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% | 43,323 psi | 68% | 2592 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 47,572 psi | 75% | 2782 fps | 99.4% |
| Accurate MAGPRO | <<locked>> | 80% | 44,860 psi | 70% | 2723 fps | 98.1% |
| ADI AR 2209 | <<locked>> | 80% | 47,355 psi | 74% | 2717 fps | 99.8% |
| ADI AR 2213 | <<locked>> | 80% | 42,612 psi | 67% | 2667 fps | 98.5% |
| ADI AR 2217 | <<locked>> | 80% | 31,778 psi | 50% | 2415 fps | 95.3% |
| ADI AR 2218 | <<locked>> | 94% | 44,179 psi | 69% | 2785 fps | 96.1% |
| ADI AR 2225 | <<locked>> | 80% | 29,138 psi | 46% | 2388 fps | 97.4% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 47,674 psi | 75% | 2717 fps | 99.8% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 47,674 psi | 75% | 2717 fps | 99.8% |
| Alliant Reloder-19 | <<locked>> | 80% | 47,239 psi | 74% | 2710 fps | 99.8% |
| Alliant Reloder-22 | <<locked>> | 80% | 43,366 psi | 68% | 2671 fps | 99.4% |
| Alliant Reloder-23 | <<locked>> | 80% | 42,105 psi | 66% | 2605 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 36,434 psi | 57% | 2556 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 47,616 psi | 75% | 2772 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 42,018 psi | 66% | 2717 fps | 95.6% |
| Alliant Reloder-50 | <<locked>> | 96% | 44,759 psi | 70% | 2766 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 41,292 psi | 65% | 2582 fps | 95.4% |
| Bofors RP15 | <<locked>> | 80% | 40,350 psi | 63% | 2608 fps | 98.8% |
| Bofors RP30 | <<locked>> | 80% | 33,953 psi | 53% | 2490 fps | 96.5% |
| Bofors RP5 | <<locked>> | 80% | 43,366 psi | 68% | 2671 fps | 99.4% |
| Hodgdon H1000 | <<locked>> | 80% | 34,519 psi | 54% | 2490 fps | 97.2% |
| Hodgdon H4831 | <<locked>> | 80% | 45,179 psi | 71% | 2664 fps | 98.5% |
| Hodgdon H4831 SC | <<locked>> | 80% | 44,382 psi | 70% | 2648 fps | 98.3% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 51,111 psi | 80% | 2687 fps | 100% |
| Hodgdon Retumbo | 91.5 gr | 80% | 35,607 psi | 56% | 2598 fps | 98.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,384 psi | 44% | 1604 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 52,968 psi | 83% | 2749 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 53,563 psi | 84% | 2749 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 46,180 psi | 72% | 2651 fps | 98.8% |
| IMR 7828 SSC | <<locked>> | 80% | 41,379 psi | 65% | 2651 fps | 98.3% |
| IMR 8133 Enduron | <<locked>> | 86% | 32,677 psi | 51% | 2480 fps | 95.8% |
| Lovex S071 | <<locked>> | 80% | 37,463 psi | 59% | 2477 fps | 99.7% |
| Norma 204 | <<locked>> | 80% | 53,969 psi | 85% | 2805 fps | 100% |
| Norma 217 | <<locked>> | 80% | 26,774 psi | 42% | 2329 fps | 95.2% |
| Norma MRP | <<locked>> | 80% | 46,064 psi | 72% | 2740 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 41,466 psi | 65% | 2661 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 80% | 54,070 psi | 85% | 2802 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 37,318 psi | 58% | 2543 fps | 99% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,153 psi | 46% | 1644 fps | 100% |
| ReloadSwiss RS 76 | 97.9 gr | 80% | 34,751 psi | 54% | 2572 fps | 99.3% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 36,956 psi | 58% | 2595 fps | 96.1% |
| Rottweil R 904 | <<locked>> | 80% | 48,138 psi | 75% | 2690 fps | 99.4% |
| Rottweil R 905 | <<locked>> | 80% | 46,862 psi | 73% | 2700 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 46,528 psi | 73% | 2697 fps | 99.8% |
| Somchem S361 | <<locked>> | 80% | 49,023 psi | 77% | 2680 fps | 99.1% |
| Somchem S365 | <<locked>> | 80% | 52,910 psi | 83% | 2743 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 47,297 psi | 74% | 2674 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 41,350 psi | 65% | 2559 fps | 99.4% |
| Vihtavuori N170 | <<locked>> | 88% | 46,180 psi | 72% | 2674 fps | 95% |
| Vihtavuori N555 | <<locked>> | 80% | 46,702 psi | 73% | 2680 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 45,745 psi | 72% | 2736 fps | 98.7% |
| Vihtavuori N565 | <<locked>> | 80% | 38,043 psi | 60% | 2562 fps | 97.1% |
| Vihtavuori N568 | <<locked>> | 84% | 38,174 psi | 60% | 2612 fps | 95.9% |
| Vihtavuori N570 | 104.5 gr | 88% | 41,872 psi | 66% | 2723 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 80% | 40,379 psi | 63% | 2671 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 43,613 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 57 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Hornady SP. ADI AR 2218 delivers the highest muzzle velocity at 2,995 fps; across all powders the maximum-charge window runs from 1,795 fps to 2,995 fps. ADI AR 2218 gives the best case fill at 100 %, and 57 of the 57 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. 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. Hodgdon Retumbo, ReloadSwiss RS 76, Vihtavuori N570 rank at the top here: for .338-378 Weath. Mag. with the .338 | 250gr | Hornady SP 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.