Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 300gr | Lapua Scenar bullet and 55 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Vihtavuori N570 and Alliant Reloder-33.
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% | 57,421 psi | 90% | 2566 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 47,950 psi | 75% | 2566 fps | 98.3% |
| Accurate High Country | <<locked>> | 82% | 55,535 psi | 87% | 2671 fps | 100% |
| Accurate MAGPRO | <<locked>> | 84% | 56,376 psi | 88% | 2680 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 54,708 psi | 86% | 2595 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 57,116 psi | 90% | 2671 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 55,956 psi | 88% | 2654 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 56,115 psi | 88% | 2792 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 96% | 55,143 psi | 86% | 2677 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 54,389 psi | 85% | 2589 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 57,609 psi | 90% | 2661 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 55,970 psi | 88% | 2569 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 56,246 psi | 88% | 2641 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 56,507 psi | 89% | 2654 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 54,041 psi | 85% | 2707 fps | 99.5% |
| Alliant Reloder-50 | <<locked>> | 98% | 53,809 psi | 84% | 2703 fps | 99.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 57,029 psi | 89% | 2638 fps | 99.7% |
| Bofors RP15 | <<locked>> | 88% | 56,971 psi | 89% | 2654 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 56,057 psi | 88% | 2671 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 57,609 psi | 90% | 2661 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 57,595 psi | 90% | 2671 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 55,869 psi | 88% | 2605 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 54,868 psi | 86% | 2592 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 55,854 psi | 88% | 2733 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,000 psi | 60% | 1627 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 56,014 psi | 88% | 2579 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 55,695 psi | 87% | 2657 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 54,578 psi | 86% | 2546 fps | 97.2% |
| IMR 8133 Enduron | <<locked>> | 98% | 54,201 psi | 85% | 2667 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 54,868 psi | 86% | 2595 fps | 96.4% |
| Lovex S071 | <<locked>> | 90% | 55,724 psi | 87% | 2543 fps | 100% |
| Norma 217 | <<locked>> | 98% | 55,579 psi | 87% | 2684 fps | 100% |
| Norma MRP | <<locked>> | 84% | 57,682 psi | 90% | 2674 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 57,043 psi | 89% | 2677 fps | 100% |
| Ramshot LRT | <<locked>> | 98% | 55,593 psi | 87% | 2720 fps | 96.4% |
| Ramshot Magnum | <<locked>> | 88% | 55,143 psi | 86% | 2608 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,044 psi | 61% | 1667 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 56,289 psi | 88% | 2723 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 55,216 psi | 87% | 2703 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 55,056 psi | 86% | 2566 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 54,215 psi | 85% | 2579 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 54,868 psi | 86% | 2595 fps | 96.4% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 50,096 psi | 79% | 2575 fps | 98.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 57,435 psi | 90% | 2625 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 56,202 psi | 88% | 2562 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 54,418 psi | 85% | 2549 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 54,491 psi | 85% | 2543 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 57,116 psi | 90% | 2635 fps | 98.9% |
| Vihtavuori N555 | <<locked>> | 82% | 54,259 psi | 85% | 2546 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 57,029 psi | 89% | 2684 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 54,491 psi | 85% | 2635 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 55,912 psi | 88% | 2703 fps | 100% |
| Vihtavuori N570 | <<locked>> | 94% | 57,290 psi | 90% | 2769 fps | 99.7% |
| Winchester StaBALL HD | <<locked>> | 86% | 56,579 psi | 89% | 2657 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 54,099 psi | 85% | 2552 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% | 47,065 psi | 74% | 2425 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 38,740 psi | 61% | 2398 fps | 95.8% |
| Accurate High Country | <<locked>> | 80% | 51,924 psi | 81% | 2618 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 49,037 psi | 77% | 2572 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 80% | 51,271 psi | 80% | 2546 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 46,514 psi | 73% | 2513 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 80% | 34,751 psi | 54% | 2297 fps | 98.5% |
| ADI AR 2218 | 98.2 gr | 86% | 36,506 psi | 57% | 2415 fps | 95.5% |
| ADI AR 2225 | <<locked>> | 80% | 32,039 psi | 50% | 2277 fps | 99.8% |
| Alliant Reloder-19 | <<locked>> | 80% | 50,952 psi | 80% | 2539 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,268 psi | 74% | 2513 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,079 psi | 72% | 2434 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,248 psi | 63% | 2408 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 52,562 psi | 82% | 2602 fps | 100% |
| Alliant Reloder-33 | 95.3 gr | 82% | 34,751 psi | 54% | 2352 fps | 95% |
| Alliant Reloder-50 | <<locked>> | 88% | 37,376 psi | 59% | 2411 fps | 95.5% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,179 psi | 69% | 2434 fps | 98.1% |
| Bofors RP15 | <<locked>> | 80% | 44,034 psi | 69% | 2457 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 37,521 psi | 59% | 2365 fps | 99.1% |
| Bofors RP5 | <<locked>> | 80% | 47,268 psi | 74% | 2513 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 37,811 psi | 59% | 2362 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 80% | 48,834 psi | 77% | 2503 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,080 psi | 75% | 2490 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 80% | 39,320 psi | 62% | 2470 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,601 psi | 45% | 1453 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,545 psi | 78% | 2487 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 45,324 psi | 71% | 2500 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 84% | 45,063 psi | 71% | 2395 fps | 95% |
| IMR 8133 Enduron | <<locked>> | 80% | 29,689 psi | 47% | 2208 fps | 96.6% |
| Lovex D100 | <<locked>> | 92% | 51,169 psi | 80% | 2539 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 40,814 psi | 64% | 2326 fps | 100% |
| Norma 217 | <<locked>> | 80% | 29,979 psi | 47% | 2231 fps | 98.8% |
| Norma MRP | <<locked>> | 80% | 50,401 psi | 79% | 2572 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 45,818 psi | 72% | 2516 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 51,967 psi | 81% | 2664 fps | 95.5% |
| Ramshot Magnum | <<locked>> | 80% | 41,234 psi | 65% | 2405 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,341 psi | 46% | 1490 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 38,653 psi | 61% | 2451 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 35,491 psi | 56% | 2359 fps | 97.5% |
| Rottweil R 904 | <<locked>> | 80% | 51,706 psi | 81% | 2520 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 50,850 psi | 80% | 2533 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 51,169 psi | 80% | 2539 fps | 95.5% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 38,203 psi | 60% | 2365 fps | 95.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,502 psi | 79% | 2530 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 52,634 psi | 82% | 2513 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 51,126 psi | 80% | 2503 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 44,788 psi | 70% | 2402 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 40,988 psi | 64% | 2369 fps | 95.5% |
| Vihtavuori N555 | <<locked>> | 80% | 50,894 psi | 80% | 2503 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 49,893 psi | 78% | 2582 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 80% | 41,742 psi | 65% | 2428 fps | 99.3% |
| Vihtavuori N568 | <<locked>> | 80% | 36,680 psi | 57% | 2372 fps | 97.3% |
| Vihtavuori N570 | 91.7 gr | 82% | 37,507 psi | 59% | 2421 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 80% | 45,266 psi | 71% | 2510 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,253 psi | 74% | 2454 fps | 100% |
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 55 powders for .338-378 Weath. Mag. loaded with the .338 | 300gr | Lapua Scenar. ADI AR 2218 delivers the highest muzzle velocity at 2,792 fps; across all powders the maximum-charge window runs from 1,627 fps to 2,792 fps. Accurate 8700 gives the best case fill at 100 %, and 55 of the 55 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 60–90 %, leaving at least 10 % headroom. The 300.0 gr projectile in 0.338" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, ReloadSwiss RS 14 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. ADI AR 2218, Vihtavuori N570, Alliant Reloder-33 rank at the top here: for .338-378 Weath. Mag. with the .338 | 300gr | Lapua Scenar 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.