Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Alaska Bullet Works Kodiak PP SPBC bullet and 51 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 80 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% | 57,435 psi | 90% | 2808 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 56,304 psi | 88% | 2923 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 84% | 54,781 psi | 86% | 2841 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 57,116 psi | 90% | 2917 fps | 100% |
| ADI AR 2217 | <<locked>> | 96% | 55,695 psi | 87% | 2894 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 55,898 psi | 88% | 3015 fps | 99.1% |
| ADI AR 2225 | <<locked>> | 98% | 54,462 psi | 85% | 2913 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 54,578 psi | 86% | 2835 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 57,537 psi | 90% | 2907 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 55,709 psi | 87% | 2815 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 55,825 psi | 87% | 2887 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 56,173 psi | 88% | 2900 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 53,621 psi | 84% | 2930 fps | 98.5% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 53,156 psi | 83% | 2917 fps | 98% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 57,377 psi | 90% | 2877 fps | 99% |
| Bofors RP15 | <<locked>> | 90% | 56,884 psi | 89% | 2900 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 55,651 psi | 87% | 2910 fps | 100% |
| Bofors RP5 | <<locked>> | 88% | 57,537 psi | 90% | 2907 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 57,319 psi | 90% | 2913 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 56,086 psi | 88% | 2848 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 86% | 54,984 psi | 86% | 2831 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 55,303 psi | 87% | 2746 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 55,042 psi | 86% | 2979 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,840 psi | 59% | 1801 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 57,000 psi | 89% | 2812 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 56,420 psi | 88% | 2825 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 88% | 55,448 psi | 87% | 2897 fps | 100% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 53,563 psi | 84% | 2897 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 55,492 psi | 87% | 2782 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 54,795 psi | 86% | 2917 fps | 100% |
| Norma MRP | <<locked>> | 86% | 57,711 psi | 90% | 2927 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 56,724 psi | 89% | 2920 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 55,013 psi | 86% | 2848 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,769 psi | 61% | 1844 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 55,724 psi | 87% | 2966 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 54,940 psi | 86% | 2936 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 84% | 55,419 psi | 87% | 2812 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 84% | 54,259 psi | 85% | 2825 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 57,537 psi | 90% | 2874 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 56,768 psi | 89% | 2805 fps | 99.8% |
| Somchem S365 | <<locked>> | 82% | 57,290 psi | 90% | 2802 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 54,563 psi | 86% | 2792 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 54,549 psi | 85% | 2782 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 57,203 psi | 90% | 2864 fps | 97.7% |
| Vihtavuori N555 | <<locked>> | 86% | 57,508 psi | 90% | 2838 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 57,087 psi | 89% | 2930 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 90% | 54,201 psi | 85% | 2867 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 94% | 55,579 psi | 87% | 2936 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 96% | 56,782 psi | 89% | 2999 fps | 98.7% |
| Winchester StaBALL HD | <<locked>> | 88% | 55,724 psi | 87% | 2904 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 54,230 psi | 85% | 2792 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% | 43,932 psi | 69% | 2605 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 45,672 psi | 72% | 2740 fps | 98.3% |
| ADI AR 2209 | <<locked>> | 80% | 47,950 psi | 75% | 2730 fps | 99.8% |
| ADI AR 2213 | <<locked>> | 80% | 43,294 psi | 68% | 2680 fps | 98.7% |
| ADI AR 2217 | <<locked>> | 80% | 32,242 psi | 51% | 2428 fps | 95.6% |
| ADI AR 2218 | <<locked>> | 92% | 41,843 psi | 66% | 2736 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 80% | 29,660 psi | 46% | 2405 fps | 97.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 47,819 psi | 75% | 2723 fps | 99.8% |
| Alliant Reloder-22 | <<locked>> | 80% | 44,063 psi | 69% | 2684 fps | 99.5% |
| Alliant Reloder-23 | <<locked>> | 80% | 42,728 psi | 67% | 2618 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 36,985 psi | 58% | 2569 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 48,530 psi | 76% | 2789 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 42,844 psi | 67% | 2733 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 42,482 psi | 67% | 2720 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 41,771 psi | 65% | 2595 fps | 95.7% |
| Bofors RP15 | <<locked>> | 80% | 40,930 psi | 64% | 2621 fps | 99% |
| Bofors RP30 | <<locked>> | 80% | 34,534 psi | 54% | 2503 fps | 96.8% |
| Bofors RP5 | <<locked>> | 80% | 44,063 psi | 69% | 2684 fps | 99.5% |
| Hodgdon H1000 | <<locked>> | 80% | 35,099 psi | 55% | 2503 fps | 97.5% |
| Hodgdon H4831 | <<locked>> | 80% | 45,847 psi | 72% | 2677 fps | 98.7% |
| Hodgdon H4831 SC | <<locked>> | 80% | 45,063 psi | 71% | 2661 fps | 98.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 51,764 psi | 81% | 2697 fps | 100% |
| Hodgdon Retumbo | 92.8 gr | 80% | 36,245 psi | 57% | 2615 fps | 98.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,398 psi | 45% | 1611 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 53,519 psi | 84% | 2759 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 46,673 psi | 73% | 2664 fps | 98.9% |
| IMR 7828 SSC | <<locked>> | 80% | 42,090 psi | 66% | 2664 fps | 98.5% |
| IMR 8133 Enduron | <<locked>> | 84% | 31,154 psi | 49% | 2441 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 37,913 psi | 59% | 2487 fps | 99.8% |
| Norma 217 | <<locked>> | 80% | 27,267 psi | 43% | 2346 fps | 95.6% |
| Norma MRP | <<locked>> | 80% | 46,804 psi | 73% | 2756 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 42,221 psi | 66% | 2680 fps | 98.9% |
| Ramshot Magnum | <<locked>> | 80% | 37,971 psi | 60% | 2556 fps | 99.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,153 psi | 46% | 1650 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 35,476 psi | 56% | 2592 fps | 99.5% |
| ReloadSwiss RS 80 | 102.6 gr | 82% | 34,954 psi | 55% | 2546 fps | 95.3% |
| Rottweil R 904 | <<locked>> | 80% | 48,689 psi | 76% | 2703 fps | 99.5% |
| Rottweil R 905 | <<locked>> | 80% | 47,500 psi | 74% | 2713 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 47,152 psi | 74% | 2710 fps | 99.8% |
| Somchem S361 | <<locked>> | 80% | 49,748 psi | 78% | 2694 fps | 99.2% |
| Somchem S365 | <<locked>> | 80% | 53,577 psi | 84% | 2753 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 48,008 psi | 75% | 2690 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 41,872 psi | 66% | 2572 fps | 99.5% |
| Vihtavuori N170 | <<locked>> | 88% | 46,818 psi | 73% | 2690 fps | 95.3% |
| Vihtavuori N555 | <<locked>> | 80% | 47,384 psi | 74% | 2690 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 46,456 psi | 73% | 2753 fps | 98.9% |
| Vihtavuori N565 | <<locked>> | 80% | 38,667 psi | 61% | 2579 fps | 97.4% |
| Vihtavuori N568 | <<locked>> | 82% | 36,245 psi | 57% | 2566 fps | 95.2% |
| Vihtavuori N570 | 105.9 gr | 88% | 42,656 psi | 67% | 2743 fps | 95.4% |
| Winchester StaBALL HD | <<locked>> | 80% | 41,205 psi | 65% | 2684 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 44,251 psi | 69% | 2625 fps | 99.5% |
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 61 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Alaska Bullet Works Kodiak PP SPBC. ADI AR 2218 delivers the highest muzzle velocity at 3,015 fps; across all powders the maximum-charge window runs from 1,801 fps to 3,015 fps. Accurate 8700 gives the best case fill at 100 %, and 61 of the 61 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 1:16.0 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. Hodgdon Retumbo, ReloadSwiss RS 80, Vihtavuori N570 rank at the top here: for .338-378 Weath. Mag. with the .338 | 250gr | Alaska Bullet Works Kodiak PP SPBC 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.