Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Sako Hammerhead 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% | 54,665 psi | 86% | 2776 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 45,310 psi | 71% | 2730 fps | 96.1% |
| Accurate MAGPRO | <<locked>> | 86% | 57,319 psi | 90% | 2940 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 84% | 55,738 psi | 87% | 2858 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 54,259 psi | 85% | 2874 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 96% | 56,869 psi | 89% | 2910 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 57,145 psi | 90% | 3038 fps | 99.3% |
| ADI AR 2225 | <<locked>> | 98% | 55,796 psi | 87% | 2933 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 55,288 psi | 87% | 2844 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 54,795 psi | 86% | 2871 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 56,666 psi | 89% | 2828 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 56,942 psi | 89% | 2904 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 57,334 psi | 90% | 2917 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 54,795 psi | 86% | 2949 fps | 98.8% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 54,433 psi | 85% | 2940 fps | 98.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 54,665 psi | 86% | 2838 fps | 98.7% |
| Bofors RP15 | <<locked>> | 90% | 57,740 psi | 90% | 2913 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 56,826 psi | 89% | 2927 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 54,795 psi | 86% | 2871 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 54,447 psi | 85% | 2874 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 56,927 psi | 89% | 2864 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 55,985 psi | 88% | 2848 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 56,188 psi | 88% | 2759 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 56,188 psi | 88% | 2995 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,840 psi | 59% | 1808 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 57,203 psi | 90% | 2841 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 88% | 56,536 psi | 89% | 2917 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 55,753 psi | 87% | 2789 fps | 95.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 54,694 psi | 86% | 2913 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 56,536 psi | 89% | 2799 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 55,985 psi | 88% | 2936 fps | 100% |
| Norma MRP | <<locked>> | 84% | 54,766 psi | 86% | 2884 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 53,838 psi | 84% | 2881 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 56,144 psi | 88% | 2864 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,885 psi | 61% | 1850 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 56,971 psi | 89% | 2982 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 56,231 psi | 88% | 2956 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 84% | 56,144 psi | 88% | 2825 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 55,172 psi | 86% | 2838 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 47,355 psi | 74% | 2743 fps | 96.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 54,795 psi | 86% | 2838 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 57,624 psi | 90% | 2822 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 55,448 psi | 87% | 2808 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 55,361 psi | 87% | 2795 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 54,476 psi | 85% | 2825 fps | 97.3% |
| Vihtavuori N555 | <<locked>> | 84% | 54,882 psi | 86% | 2805 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 54,201 psi | 85% | 2887 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 55,187 psi | 86% | 2884 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 94% | 56,681 psi | 89% | 2956 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 94% | 53,998 psi | 85% | 2956 fps | 98.3% |
| Winchester StaBALL HD | <<locked>> | 88% | 56,956 psi | 89% | 2920 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 55,201 psi | 87% | 2808 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% | 44,802 psi | 70% | 2618 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 42,090 psi | 66% | 2667 fps | 95% |
| Accurate MAGPRO | <<locked>> | 80% | 46,543 psi | 73% | 2756 fps | 98.6% |
| ADI AR 2209 | <<locked>> | 80% | 48,733 psi | 76% | 2746 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 44,048 psi | 69% | 2697 fps | 98.9% |
| ADI AR 2217 | <<locked>> | 80% | 32,808 psi | 51% | 2448 fps | 96% |
| ADI AR 2218 | <<locked>> | 92% | 42,656 psi | 67% | 2756 fps | 95.8% |
| ADI AR 2225 | <<locked>> | 80% | 30,226 psi | 47% | 2421 fps | 98% |
| Alliant Reloder-19 | <<locked>> | 80% | 48,704 psi | 76% | 2740 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 44,817 psi | 70% | 2700 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 43,569 psi | 68% | 2631 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 37,753 psi | 59% | 2585 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 49,559 psi | 78% | 2805 fps | 100% |
| Alliant Reloder-33 | 111.9 gr | 88% | 40,727 psi | 64% | 2687 fps | 95.3% |
| Alliant Reloder-50 | <<locked>> | 94% | 43,555 psi | 68% | 2743 fps | 95.7% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 42,250 psi | 66% | 2608 fps | 96% |
| Bofors RP15 | <<locked>> | 80% | 41,669 psi | 65% | 2638 fps | 99.2% |
| Bofors RP30 | <<locked>> | 80% | 35,360 psi | 55% | 2526 fps | 97.2% |
| Bofors RP5 | <<locked>> | 80% | 44,817 psi | 70% | 2700 fps | 99.7% |
| Hodgdon H1000 | <<locked>> | 80% | 35,752 psi | 56% | 2523 fps | 97.8% |
| Hodgdon H4831 | <<locked>> | 80% | 46,572 psi | 73% | 2694 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 45,774 psi | 72% | 2677 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 52,634 psi | 82% | 2713 fps | 100% |
| Hodgdon Retumbo | 94.3 gr | 80% | 36,956 psi | 58% | 2635 fps | 99.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,427 psi | 45% | 1617 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 47,355 psi | 74% | 2677 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 80% | 42,873 psi | 67% | 2680 fps | 98.7% |
| IMR 7977 Enduron | <<locked>> | 90% | 52,330 psi | 82% | 2733 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 84% | 31,792 psi | 50% | 2457 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 38,682 psi | 61% | 2503 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 27,891 psi | 44% | 2365 fps | 96% |
| Norma MRP | <<locked>> | 80% | 47,630 psi | 75% | 2769 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 43,033 psi | 67% | 2697 fps | 99.1% |
| Ramshot Magnum | <<locked>> | 80% | 38,682 psi | 61% | 2572 fps | 99.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,196 psi | 46% | 1654 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 36,216 psi | 57% | 2608 fps | 99.6% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 35,694 psi | 56% | 2566 fps | 95.7% |
| Rottweil R 904 | <<locked>> | 80% | 49,443 psi | 77% | 2717 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 48,298 psi | 76% | 2730 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 44,193 psi | 69% | 2684 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 47,950 psi | 75% | 2726 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 50,488 psi | 79% | 2710 fps | 99.4% |
| Somchem S385 | <<locked>> | 80% | 48,733 psi | 76% | 2703 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 42,699 psi | 67% | 2589 fps | 99.6% |
| Vihtavuori N170 | <<locked>> | 88% | 47,630 psi | 75% | 2707 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 48,225 psi | 76% | 2707 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 47,181 psi | 74% | 2766 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 80% | 39,378 psi | 62% | 2595 fps | 97.6% |
| Vihtavuori N568 | <<locked>> | 82% | 37,028 psi | 58% | 2582 fps | 95.6% |
| Vihtavuori N570 | 107.6 gr | 88% | 43,584 psi | 68% | 2762 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 42,177 psi | 66% | 2697 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 44,962 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 52 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Sako Hammerhead. ADI AR 2218 delivers the highest muzzle velocity at 3,038 fps; across all powders the maximum-charge window runs from 1,808 fps to 3,038 fps. Accurate 8700 gives the best case fill at 100 %, and 52 of the 52 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 | Sako Hammerhead 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.