Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 265gr | Barnes TAC-TX BT bullet and 66 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% | 57,217 psi | 90% | 2723 fps | 100% |
| Accurate High Country | <<locked>> | 86% | 55,347 psi | 87% | 2831 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 56,188 psi | 88% | 2838 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 86% | 55,187 psi | 86% | 2762 fps | 100% |
| ADI AR 2213 | <<locked>> | 90% | 57,246 psi | 90% | 2835 fps | 100% |
| ADI AR 2217 | <<locked>> | 98% | 55,463 psi | 87% | 2808 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 51,619 psi | 81% | 2861 fps | 98.4% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 53,679 psi | 84% | 2825 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 55,347 psi | 87% | 2759 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 55,347 psi | 87% | 2759 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 55,535 psi | 87% | 2743 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 54,752 psi | 86% | 2753 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 90% | 57,493 psi | 90% | 2825 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 55,463 psi | 87% | 2730 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 55,492 psi | 87% | 2802 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 55,796 psi | 87% | 2815 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 56,826 psi | 89% | 2904 fps | 99.1% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 47,848 psi | 75% | 2759 fps | 97.1% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 54,172 psi | 85% | 2743 fps | 98.7% |
| Bofors RP15 | <<locked>> | 92% | 56,608 psi | 89% | 2812 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 54,998 psi | 86% | 2818 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 57,493 psi | 90% | 2825 fps | 100% |
| Hodgdon H1000 | <<locked>> | 96% | 57,087 psi | 89% | 2828 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 56,536 psi | 89% | 2769 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 88% | 55,303 psi | 87% | 2753 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 55,593 psi | 87% | 2667 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 54,331 psi | 85% | 2887 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,507 psi | 59% | 1716 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 57,653 psi | 90% | 2733 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 54,491 psi | 85% | 2680 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 56,913 psi | 89% | 2746 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 90% | 55,521 psi | 87% | 2815 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 94% | 55,390 psi | 87% | 2694 fps | 95.8% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 49,139 psi | 77% | 2753 fps | 99.8% |
| Lovex S070 | <<locked>> | 82% | 56,101 psi | 88% | 2707 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 55,056 psi | 86% | 2697 fps | 100% |
| Norma 204 | <<locked>> | 82% | 55,158 psi | 86% | 2740 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 49,777 psi | 78% | 2769 fps | 100% |
| Norma MRP | <<locked>> | 88% | 57,580 psi | 90% | 2838 fps | 100% |
| Norma URP | <<locked>> | 82% | 56,072 psi | 88% | 2720 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 56,652 psi | 89% | 2838 fps | 100% |
| Ramshot Hunter | <<locked>> | 82% | 55,071 psi | 86% | 2733 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 54,810 psi | 86% | 2766 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,450 psi | 60% | 1759 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 56,782 psi | 89% | 2792 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 54,969 psi | 86% | 2877 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 53,998 psi | 85% | 2844 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 86% | 55,869 psi | 88% | 2733 fps | 100% |
| Rottweil R 905 | <<locked>> | 86% | 54,389 psi | 85% | 2743 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 56,101 psi | 88% | 2707 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 56,724 psi | 89% | 2664 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 57,696 psi | 90% | 2789 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 57,290 psi | 90% | 2726 fps | 99.9% |
| Somchem S365 | <<locked>> | 84% | 57,435 psi | 90% | 2723 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 54,665 psi | 86% | 2710 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 54,650 psi | 86% | 2700 fps | 100% |
| Vihtavuori N170 | <<locked>> | 96% | 56,985 psi | 89% | 2779 fps | 97.7% |
| Vihtavuori N550 | <<locked>> | 82% | 56,884 psi | 89% | 2720 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 57,261 psi | 90% | 2753 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 57,116 psi | 90% | 2848 fps | 100% |
| Vihtavuori N565 | <<locked>> | 94% | 57,493 psi | 90% | 2835 fps | 100% |
| Vihtavuori N568 | <<locked>> | 96% | 54,926 psi | 86% | 2848 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 98% | 56,130 psi | 88% | 2910 fps | 98.7% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 57,159 psi | 90% | 2664 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 54,853 psi | 86% | 2815 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 54,549 psi | 85% | 2713 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% | 40,567 psi | 64% | 2470 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 44,715 psi | 70% | 2654 fps | 99.2% |
| Accurate MAGPRO | <<locked>> | 80% | 42,250 psi | 66% | 2598 fps | 97.8% |
| ADI AR 2209 | <<locked>> | 80% | 45,121 psi | 71% | 2602 fps | 99.7% |
| ADI AR 2213 | <<locked>> | 80% | 40,364 psi | 63% | 2549 fps | 98.3% |
| ADI AR 2217 | <<locked>> | 82% | 31,937 psi | 50% | 2356 fps | 95.8% |
| ADI AR 2218 | <<locked>> | 94% | 41,379 psi | 65% | 2654 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 80% | 27,137 psi | 43% | 2270 fps | 96.7% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 45,339 psi | 71% | 2598 fps | 99.7% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 45,339 psi | 71% | 2598 fps | 99.7% |
| Alliant Reloder-16 | <<locked>> | 80% | 51,924 psi | 81% | 2694 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 44,918 psi | 70% | 2592 fps | 99.7% |
| Alliant Reloder-22 | <<locked>> | 80% | 40,915 psi | 64% | 2552 fps | 99.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 39,653 psi | 62% | 2490 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 34,142 psi | 54% | 2438 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 80% | 44,527 psi | 70% | 2648 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 41,887 psi | 66% | 2648 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 96% | 41,031 psi | 64% | 2628 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 39,465 psi | 62% | 2470 fps | 95.1% |
| Bofors RP15 | <<locked>> | 80% | 38,000 psi | 60% | 2490 fps | 98.6% |
| Bofors RP30 | <<locked>> | 80% | 31,488 psi | 49% | 2369 fps | 95.9% |
| Bofors RP5 | <<locked>> | 80% | 40,915 psi | 64% | 2552 fps | 99.2% |
| Hodgdon H1000 | <<locked>> | 80% | 32,460 psi | 51% | 2372 fps | 96.7% |
| Hodgdon H4831 | <<locked>> | 80% | 42,888 psi | 67% | 2546 fps | 98.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 42,192 psi | 66% | 2533 fps | 98.1% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 48,805 psi | 76% | 2572 fps | 100% |
| Hodgdon Retumbo | 85.3 gr | 80% | 33,315 psi | 52% | 2477 fps | 98.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,166 psi | 44% | 1535 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 50,821 psi | 80% | 2635 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 51,053 psi | 80% | 2635 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 44,179 psi | 69% | 2539 fps | 98.6% |
| IMR 7828 SSC | <<locked>> | 80% | 39,015 psi | 61% | 2530 fps | 98% |
| IMR 7977 Enduron | <<locked>> | 92% | 51,924 psi | 81% | 2638 fps | 95% |
| IMR 8133 Enduron | <<locked>> | 86% | 30,211 psi | 47% | 2356 fps | 95.1% |
| Lovex S070 | <<locked>> | 80% | 52,678 psi | 83% | 2657 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 34,896 psi | 55% | 2356 fps | 99.5% |
| Norma 204 | <<locked>> | 80% | 51,503 psi | 81% | 2687 fps | 100% |
| Norma 217 | <<locked>> | 82% | 26,324 psi | 41% | 2264 fps | 95.5% |
| Norma MRP | <<locked>> | 80% | 43,250 psi | 68% | 2618 fps | 100% |
| Norma URP | <<locked>> | 80% | 52,533 psi | 82% | 2674 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 38,856 psi | 61% | 2539 fps | 98.3% |
| Ramshot Hunter | <<locked>> | 80% | 51,474 psi | 81% | 2684 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 34,635 psi | 54% | 2421 fps | 98.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,805 psi | 45% | 1572 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 52,924 psi | 83% | 2740 fps | 100% |
| ReloadSwiss RS 76 | 91.3 gr | 80% | 32,329 psi | 51% | 2448 fps | 98.9% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 33,982 psi | 53% | 2464 fps | 95.3% |
| Rottweil R 904 | <<locked>> | 80% | 45,948 psi | 72% | 2575 fps | 99.2% |
| Rottweil R 905 | <<locked>> | 80% | 44,498 psi | 70% | 2582 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 80% | 52,678 psi | 83% | 2657 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 53,011 psi | 83% | 2612 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 44,164 psi | 69% | 2579 fps | 99.6% |
| Somchem S361 | <<locked>> | 80% | 46,818 psi | 73% | 2566 fps | 98.9% |
| Somchem S365 | <<locked>> | 80% | 50,212 psi | 79% | 2628 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 44,875 psi | 70% | 2559 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 39,030 psi | 61% | 2444 fps | 99.2% |
| Vihtavuori N170 | <<locked>> | 90% | 46,499 psi | 73% | 2608 fps | 95.4% |
| Vihtavuori N550 | <<locked>> | 80% | 53,258 psi | 83% | 2671 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 44,048 psi | 69% | 2562 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 43,091 psi | 68% | 2615 fps | 98.5% |
| Vihtavuori N565 | <<locked>> | 80% | 35,491 psi | 56% | 2441 fps | 96.6% |
| Vihtavuori N568 | <<locked>> | 84% | 35,462 psi | 56% | 2484 fps | 95.2% |
| Vihtavuori N570 | 99.6 gr | 90% | 41,858 psi | 66% | 2657 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 53,345 psi | 84% | 2618 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 37,202 psi | 58% | 2546 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 41,263 psi | 65% | 2497 fps | 99.2% |
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 66 powders for .338-378 Weath. Mag. loaded with the .338 | 265gr | Barnes TAC-TX BT. Vihtavuori N570 delivers the highest muzzle velocity at 2,910 fps; across all powders the maximum-charge window runs from 1,716 fps to 2,910 fps. ADI AR 2218 gives the best case fill at 100 %, and 66 of the 66 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 265.0 gr projectile in 0.338" calls for a 1:10.5 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 | 265gr | Barnes TAC-TX BT 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.