Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 300gr | Nosler AccuBond bullet and 56 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon H4831, ADI AR 2218 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>> | 86% | 57,696 psi | 90% | 2569 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 48,269 psi | 76% | 2572 fps | 98.4% |
| Accurate High Country | <<locked>> | 82% | 55,825 psi | 87% | 2674 fps | 100% |
| Accurate MAGPRO | <<locked>> | 84% | 56,637 psi | 89% | 2687 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 54,969 psi | 86% | 2598 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 57,377 psi | 90% | 2674 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 56,362 psi | 88% | 2661 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 56,289 psi | 88% | 2795 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 96% | 55,550 psi | 87% | 2680 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 82% | 55,042 psi | 86% | 2595 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 54,505 psi | 85% | 2592 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 54,157 psi | 85% | 2615 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 56,057 psi | 88% | 2569 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 56,536 psi | 89% | 2648 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 56,782 psi | 89% | 2657 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 54,244 psi | 85% | 2710 fps | 99.6% |
| Alliant Reloder-50 | <<locked>> | 98% | 54,143 psi | 85% | 2710 fps | 99.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 57,348 psi | 90% | 2644 fps | 99.8% |
| Bofors RP15 | <<locked>> | 88% | 57,232 psi | 90% | 2657 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 56,318 psi | 88% | 2674 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 54,157 psi | 85% | 2615 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 53,867 psi | 84% | 2625 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 56,115 psi | 88% | 2608 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 55,071 psi | 86% | 2595 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 56,144 psi | 88% | 2736 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,072 psi | 60% | 1631 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 56,246 psi | 88% | 2585 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 55,970 psi | 88% | 2661 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 54,766 psi | 86% | 2549 fps | 97.3% |
| IMR 8133 Enduron | <<locked>> | 98% | 54,578 psi | 86% | 2674 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 55,201 psi | 87% | 2602 fps | 96.5% |
| Lovex S071 | <<locked>> | 90% | 55,985 psi | 88% | 2549 fps | 100% |
| Norma 217 | <<locked>> | 98% | 55,999 psi | 88% | 2690 fps | 100% |
| Norma MRP | <<locked>> | 82% | 54,201 psi | 85% | 2628 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 57,305 psi | 90% | 2680 fps | 100% |
| Ramshot LRT | <<locked>> | 98% | 55,956 psi | 88% | 2726 fps | 96.5% |
| Ramshot Magnum | <<locked>> | 88% | 55,550 psi | 87% | 2615 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,117 psi | 61% | 1670 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 56,536 psi | 89% | 2723 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 55,637 psi | 87% | 2710 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 55,303 psi | 87% | 2569 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 54,462 psi | 85% | 2582 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 55,201 psi | 87% | 2602 fps | 96.5% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 50,459 psi | 79% | 2582 fps | 98.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 57,667 psi | 90% | 2628 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 56,420 psi | 88% | 2566 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 54,679 psi | 86% | 2556 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 54,723 psi | 86% | 2546 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 57,290 psi | 90% | 2638 fps | 98.9% |
| Vihtavuori N555 | <<locked>> | 82% | 54,389 psi | 85% | 2549 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 57,290 psi | 90% | 2690 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 54,723 psi | 86% | 2638 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 56,333 psi | 88% | 2710 fps | 100% |
| Vihtavuori N570 | <<locked>> | 94% | 57,696 psi | 90% | 2776 fps | 99.7% |
| Winchester StaBALL HD | <<locked>> | 86% | 56,884 psi | 89% | 2661 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 54,331 psi | 85% | 2556 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% | 47,340 psi | 74% | 2431 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 39,001 psi | 61% | 2405 fps | 96% |
| Accurate High Country | <<locked>> | 80% | 52,025 psi | 82% | 2621 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 49,284 psi | 77% | 2575 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 80% | 51,387 psi | 81% | 2549 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 46,644 psi | 73% | 2516 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 80% | 34,954 psi | 55% | 2300 fps | 98.6% |
| ADI AR 2218 | 98.6 gr | 86% | 36,666 psi | 57% | 2421 fps | 95.6% |
| ADI AR 2225 | <<locked>> | 80% | 32,242 psi | 51% | 2283 fps | 99.8% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 51,677 psi | 81% | 2546 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,198 psi | 80% | 2543 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,398 psi | 74% | 2513 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,224 psi | 72% | 2438 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,379 psi | 63% | 2408 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 52,852 psi | 83% | 2605 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 34,940 psi | 55% | 2356 fps | 95.1% |
| Alliant Reloder-50 | <<locked>> | 88% | 37,550 psi | 59% | 2411 fps | 95.5% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,382 psi | 70% | 2441 fps | 98.1% |
| Bofors RP15 | <<locked>> | 80% | 44,280 psi | 69% | 2464 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 37,753 psi | 59% | 2369 fps | 99.2% |
| Bofors RP5 | <<locked>> | 80% | 47,398 psi | 74% | 2513 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 37,913 psi | 59% | 2362 fps | 99.5% |
| Hodgdon H4831 | 87.6 gr | 80% | 49,052 psi | 77% | 2507 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,167 psi | 75% | 2493 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 80% | 39,566 psi | 62% | 2474 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,587 psi | 45% | 1453 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,632 psi | 78% | 2487 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 45,571 psi | 71% | 2503 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 84% | 45,281 psi | 71% | 2398 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 80% | 29,805 psi | 47% | 2211 fps | 96.7% |
| Lovex D100 | <<locked>> | 92% | 51,314 psi | 80% | 2543 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 40,944 psi | 64% | 2329 fps | 100% |
| Norma 217 | <<locked>> | 80% | 30,182 psi | 47% | 2238 fps | 98.8% |
| Norma MRP | <<locked>> | 80% | 50,502 psi | 79% | 2575 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,064 psi | 72% | 2520 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 52,170 psi | 82% | 2664 fps | 95.6% |
| Ramshot Magnum | <<locked>> | 80% | 41,452 psi | 65% | 2408 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,443 psi | 46% | 1493 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 38,783 psi | 61% | 2451 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 35,708 psi | 56% | 2365 fps | 97.6% |
| Rottweil R 904 | <<locked>> | 80% | 51,953 psi | 81% | 2523 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 50,952 psi | 80% | 2533 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 51,314 psi | 80% | 2543 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 38,493 psi | 60% | 2372 fps | 95.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,604 psi | 79% | 2530 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 52,808 psi | 83% | 2516 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 51,227 psi | 80% | 2507 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,049 psi | 71% | 2405 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 41,191 psi | 65% | 2375 fps | 95.6% |
| Vihtavuori N555 | <<locked>> | 80% | 51,039 psi | 80% | 2503 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 49,995 psi | 78% | 2582 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 41,843 psi | 66% | 2431 fps | 99.4% |
| Vihtavuori N568 | <<locked>> | 80% | 36,912 psi | 58% | 2375 fps | 97.4% |
| Vihtavuori N570 | 92.1 gr | 82% | 37,739 psi | 59% | 2425 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 80% | 45,571 psi | 71% | 2513 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,456 psi | 74% | 2457 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 56 powders for .338-378 Weath. Mag. loaded with the .338 | 300gr | Nosler AccuBond. ADI AR 2218 delivers the highest muzzle velocity at 2,795 fps; across all powders the maximum-charge window runs from 1,631 fps to 2,795 fps. Accurate 8700 gives the best case fill at 100 %, and 56 of the 56 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 1:12.0 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. Hodgdon H4831, ADI AR 2218, Vihtavuori N570 rank at the top here: for .338-378 Weath. Mag. with the .338 | 300gr | Nosler AccuBond 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.