Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Nosler Expansion Tip bullet and 65 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>> | 90% | 57,334 psi | 90% | 2799 fps | 100% |
| Accurate High Country | <<locked>> | 86% | 55,245 psi | 87% | 2904 fps | 99.9% |
| Accurate MAGPRO | <<locked>> | 88% | 56,231 psi | 88% | 2910 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 86% | 55,085 psi | 86% | 2835 fps | 100% |
| ADI AR 2213 | <<locked>> | 90% | 57,043 psi | 89% | 2907 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 98% | 55,216 psi | 87% | 2877 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 51,503 psi | 81% | 2923 fps | 97.9% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 53,534 psi | 84% | 2897 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 55,317 psi | 87% | 2831 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 55,317 psi | 87% | 2818 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 54,708 psi | 86% | 2825 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 90% | 57,392 psi | 90% | 2897 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 55,361 psi | 87% | 2805 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 55,230 psi | 87% | 2874 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 55,912 psi | 88% | 2897 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 56,710 psi | 89% | 2972 fps | 98.7% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 48,109 psi | 75% | 2828 fps | 96.6% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 57,595 psi | 90% | 2867 fps | 98.8% |
| Bofors RP15 | <<locked>> | 92% | 56,565 psi | 89% | 2887 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 54,940 psi | 86% | 2894 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 57,392 psi | 90% | 2897 fps | 100% |
| Hodgdon H1000 | <<locked>> | 96% | 56,797 psi | 89% | 2897 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 56,289 psi | 88% | 2838 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 88% | 55,303 psi | 87% | 2825 fps | 99.6% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 55,419 psi | 87% | 2740 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 54,172 psi | 85% | 2963 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,594 psi | 59% | 1775 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 57,522 psi | 90% | 2805 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 54,636 psi | 86% | 2759 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 56,782 psi | 89% | 2815 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 90% | 55,201 psi | 87% | 2887 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 49,124 psi | 77% | 2822 fps | 99.7% |
| Lovex S070 | <<locked>> | 82% | 56,260 psi | 88% | 2782 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 55,274 psi | 87% | 2772 fps | 100% |
| Norma 204 | <<locked>> | 82% | 54,984 psi | 86% | 2812 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 49,879 psi | 78% | 2844 fps | 100% |
| Norma MRP | <<locked>> | 88% | 57,464 psi | 90% | 2917 fps | 100% |
| Norma URP | <<locked>> | 82% | 56,130 psi | 88% | 2799 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 56,318 psi | 88% | 2910 fps | 100% |
| Ramshot Hunter | <<locked>> | 82% | 54,926 psi | 86% | 2808 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 54,650 psi | 86% | 2838 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,537 psi | 60% | 1818 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 56,579 psi | 89% | 2867 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 54,737 psi | 86% | 2953 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 53,998 psi | 85% | 2917 fps | 99.6% |
| Rottweil R 904 | <<locked>> | 86% | 55,869 psi | 88% | 2805 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 86% | 54,433 psi | 85% | 2815 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 56,260 psi | 88% | 2782 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 56,666 psi | 89% | 2736 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 57,609 psi | 90% | 2864 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 57,232 psi | 90% | 2799 fps | 99.7% |
| Somchem S365 | <<locked>> | 84% | 57,363 psi | 90% | 2799 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 54,766 psi | 86% | 2785 fps | 100% |
| Vihtavuori N160 | <<locked>> | 82% | 57,551 psi | 90% | 2785 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 54,505 psi | 85% | 2772 fps | 100% |
| Vihtavuori N170 | <<locked>> | 96% | 57,058 psi | 89% | 2848 fps | 97.3% |
| Vihtavuori N550 | <<locked>> | 82% | 56,869 psi | 89% | 2795 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 57,421 psi | 90% | 2831 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 56,985 psi | 89% | 2920 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 94% | 57,522 psi | 90% | 2910 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 96% | 54,810 psi | 86% | 2917 fps | 99.3% |
| Vihtavuori N570 | <<locked>> | 98% | 55,883 psi | 88% | 2979 fps | 98.3% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 57,000 psi | 89% | 2736 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 54,708 psi | 86% | 2894 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 54,418 psi | 85% | 2782 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% | 41,133 psi | 64% | 2546 fps | 99.9% |
| Accurate High Country | <<locked>> | 80% | 44,947 psi | 70% | 2726 fps | 98.9% |
| Accurate MAGPRO | <<locked>> | 80% | 42,337 psi | 66% | 2667 fps | 97.3% |
| ADI AR 2209 | <<locked>> | 80% | 45,078 psi | 71% | 2667 fps | 99.4% |
| ADI AR 2213 | <<locked>> | 80% | 40,350 psi | 63% | 2612 fps | 97.8% |
| ADI AR 2217 | <<locked>> | 82% | 32,227 psi | 51% | 2421 fps | 95.2% |
| ADI AR 2218 | <<locked>> | 96% | 44,599 psi | 70% | 2785 fps | 95.8% |
| ADI AR 2225 | <<locked>> | 80% | 27,586 psi | 43% | 2336 fps | 96.2% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 45,484 psi | 71% | 2671 fps | 99.5% |
| Alliant Reloder-16 | <<locked>> | 80% | 51,837 psi | 81% | 2769 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 45,063 psi | 71% | 2664 fps | 99.4% |
| Alliant Reloder-22 | <<locked>> | 80% | 41,017 psi | 64% | 2621 fps | 98.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 39,827 psi | 62% | 2562 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 34,360 psi | 54% | 2507 fps | 99.7% |
| Alliant Reloder-26 | <<locked>> | 80% | 44,730 psi | 70% | 2723 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 42,047 psi | 66% | 2713 fps | 95.3% |
| Alliant Reloder-50 | <<locked>> | 98% | 44,541 psi | 70% | 2762 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 42,105 psi | 66% | 2589 fps | 95.3% |
| Bofors RP15 | <<locked>> | 80% | 38,174 psi | 60% | 2559 fps | 98.2% |
| Bofors RP30 | <<locked>> | 80% | 31,894 psi | 50% | 2438 fps | 95.4% |
| Bofors RP5 | <<locked>> | 80% | 41,017 psi | 64% | 2621 fps | 98.9% |
| Hodgdon H1000 | <<locked>> | 80% | 32,663 psi | 51% | 2434 fps | 96.1% |
| Hodgdon H4831 | <<locked>> | 80% | 42,989 psi | 67% | 2612 fps | 97.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 42,206 psi | 66% | 2598 fps | 97.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 48,878 psi | 77% | 2648 fps | 100% |
| Hodgdon Retumbo | 87.2 gr | 80% | 33,605 psi | 53% | 2543 fps | 97.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,224 psi | 44% | 1585 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 50,763 psi | 80% | 2707 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 51,169 psi | 80% | 2707 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 44,208 psi | 69% | 2605 fps | 98.2% |
| IMR 7828 SSC | <<locked>> | 80% | 39,175 psi | 61% | 2595 fps | 97.6% |
| IMR 8133 Enduron | <<locked>> | 88% | 32,750 psi | 51% | 2484 fps | 95.7% |
| Lovex S070 | <<locked>> | 80% | 52,750 psi | 83% | 2733 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 35,491 psi | 56% | 2431 fps | 99.4% |
| Norma 204 | <<locked>> | 80% | 51,459 psi | 81% | 2756 fps | 99.9% |
| Norma 217 | <<locked>> | 82% | 26,861 psi | 42% | 2333 fps | 95% |
| Norma MRP | <<locked>> | 80% | 43,497 psi | 68% | 2690 fps | 99.9% |
| Norma URP | <<locked>> | 80% | 52,547 psi | 82% | 2746 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 38,957 psi | 61% | 2605 fps | 97.9% |
| Ramshot Hunter | <<locked>> | 80% | 51,503 psi | 81% | 2756 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 34,969 psi | 55% | 2490 fps | 98.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,993 psi | 45% | 1624 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 52,692 psi | 83% | 2815 fps | 100% |
| ReloadSwiss RS 76 | 93.3 gr | 80% | 32,692 psi | 51% | 2516 fps | 98.6% |
| ReloadSwiss RS 80 | <<locked>> | 86% | 37,057 psi | 58% | 2598 fps | 95.9% |
| Rottweil R 904 | <<locked>> | 80% | 46,093 psi | 72% | 2644 fps | 98.9% |
| Rottweil R 905 | <<locked>> | 80% | 44,585 psi | 70% | 2651 fps | 99.5% |
| Shooters World SW4350 | <<locked>> | 80% | 52,750 psi | 83% | 2733 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 53,272 psi | 83% | 2687 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 44,251 psi | 69% | 2648 fps | 99.4% |
| Somchem S361 | <<locked>> | 80% | 46,847 psi | 73% | 2631 fps | 98.5% |
| Somchem S365 | <<locked>> | 80% | 50,241 psi | 79% | 2703 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 45,034 psi | 71% | 2628 fps | 99.8% |
| Vihtavuori N160 | <<locked>> | 80% | 54,056 psi | 85% | 2736 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 39,305 psi | 62% | 2513 fps | 98.9% |
| Vihtavuori N170 | <<locked>> | 92% | 49,893 psi | 78% | 2733 fps | 95.7% |
| Vihtavuori N550 | <<locked>> | 80% | 53,345 psi | 84% | 2743 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 44,338 psi | 69% | 2635 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 43,294 psi | 68% | 2684 fps | 98.1% |
| Vihtavuori N565 | <<locked>> | 80% | 35,752 psi | 56% | 2510 fps | 96.1% |
| Vihtavuori N568 | <<locked>> | 86% | 38,363 psi | 60% | 2612 fps | 95.7% |
| Vihtavuori N570 | 104 gr | 92% | 45,034 psi | 71% | 2789 fps | 95.9% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 53,301 psi | 84% | 2690 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 37,333 psi | 59% | 2618 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 41,437 psi | 65% | 2566 fps | 98.9% |
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 65 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Nosler Expansion Tip. Vihtavuori N570 delivers the highest muzzle velocity at 2,979 fps; across all powders the maximum-charge window runs from 1,775 fps to 2,979 fps. ADI AR 2218 gives the best case fill at 100 %, and 65 of the 65 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 1:11.0 twist; slower twists will usually not stabilise this weight. ADI AR 2218, ADI AR 2225, Alliant Reloder-33 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 Expansion Tip 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.