Load Specifications
Bullet:.338 | 250gr | Barnes MRX BT
Bullet Manufacturer:Barnes
Bullet Weight:250 gr
Bullet Diameter:0.338"
Bullet Length:<<locked>>
Caliber:.340 Weath. Mag. load data
Case Length (l3):2.825"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:100 Grains of Water
Primer Size:Large Rifle Magnum (LRM)
Barrel Length:26"
Max. allowed Pressure:63,817 psi
Recommended Twist Rate:1:14.0
Load data in caliber .340 Weath. Mag. with .338 | 250gr | Barnes MRX BT bullet and 107 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, Accurate High Country and ReloadSwiss RS 70.
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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 84% | 57,667 psi | 90% | 2575 fps | 100% |
| Accurate 2700 | <<locked>> | 84% | 55,724 psi | 87% | 2615 fps | 99.5% |
| Accurate 3100ᴾ | <<locked>> | 100% | 52,895 psi | 83% | 2657 fps | 100% |
| Accurate 4064 | <<locked>> | 84% | 54,520 psi | 85% | 2585 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 55,317 psi | 87% | 2697 fps | 100% |
| Accurate High Country | <<locked>> | 98% | 54,331 psi | 85% | 2802 fps | 98.6% |
| Accurate MAGPROᴾ | <<locked>> | 100% | 55,332 psi | 87% | 2802 fps | 97.6% |
| ADI AR 2206H | <<locked>> | 82% | 57,450 psi | 90% | 2664 fps | 100% |
| ADI AR 2208 | <<locked>> | 86% | 55,100 psi | 86% | 2625 fps | 100% |
| ADI AR 2209 | <<locked>> | 98% | 56,507 psi | 89% | 2749 fps | 99.3% |
| ADI AR 2213ᴾ | <<locked>> | 100% | 54,201 psi | 85% | 2749 fps | 98.2% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 54,418 psi | 85% | 2743 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 56,724 psi | 89% | 2749 fps | 99.3% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 56,724 psi | 89% | 2749 fps | 99.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 55,782 psi | 87% | 2644 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 55,970 psi | 88% | 2664 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 94% | 56,507 psi | 89% | 2753 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 88% | 54,012 psi | 85% | 2723 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 55,912 psi | 88% | 2740 fps | 99.3% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 52,968 psi | 83% | 2743 fps | 99.1% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 49,908 psi | 78% | 2671 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 43,395 psi | 68% | 2615 fps | 99.8% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 57,566 psi | 90% | 2861 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 57,522 psi | 90% | 2687 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 48,530 psi | 76% | 2674 fps | 98.4% |
| Bofors RP3 | <<locked>> | 86% | 56,405 psi | 88% | 2657 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 52,968 psi | 83% | 2743 fps | 99.1% |
| Bofors RP7 | <<locked>> | 90% | 55,840 psi | 88% | 2654 fps | 99.6% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 43,178 psi | 68% | 2552 fps | 96.5% |
| Hodgdon H380 | <<locked>> | 86% | 57,072 psi | 89% | 2680 fps | 100% |
| Hodgdon H414 | <<locked>> | 90% | 54,172 psi | 85% | 2703 fps | 99.8% |
| Hodgdon H4350 | <<locked>> | 90% | 57,609 psi | 90% | 2713 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 98% | 54,346 psi | 85% | 2694 fps | 97.6% |
| Hodgdon H4831 SCᴾ | <<locked>> | 100% | 56,985 psi | 89% | 2733 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 56,666 psi | 89% | 2674 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 54,665 psi | 86% | 2661 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 42,525 psi | 67% | 2648 fps | 97.9% |
| Hodgdon Superformance | <<locked>> | 90% | 54,288 psi | 85% | 2743 fps | 99.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,303 psi | 57% | 1614 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 55,448 psi | 87% | 2625 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 54,592 psi | 86% | 2608 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 57,261 psi | 90% | 2644 fps | 99.9% |
| IMR 4350 | <<locked>> | 94% | 56,956 psi | 89% | 2687 fps | 99.7% |
| IMR 4451 Enduron | <<locked>> | 90% | 57,725 psi | 90% | 2680 fps | 99.9% |
| IMR 4831 | <<locked>> | 94% | 55,825 psi | 87% | 2690 fps | 100% |
| IMR 4895 | <<locked>> | 84% | 57,450 psi | 90% | 2690 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 55,898 psi | 88% | 2680 fps | 98% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 51,619 psi | 81% | 2723 fps | 97.9% |
| Lovex D073.6 | <<locked>> | 82% | 57,740 psi | 90% | 2635 fps | 100% |
| Lovex S060 | <<locked>> | 82% | 56,159 psi | 88% | 2589 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 54,563 psi | 86% | 2598 fps | 100% |
| Lovex S065 | <<locked>> | 92% | 57,711 psi | 90% | 2674 fps | 100% |
| Lovex S070 | <<locked>> | 92% | 55,347 psi | 87% | 2667 fps | 99.9% |
| Lovex S071ᴾ | <<locked>> | 100% | 43,787 psi | 69% | 2516 fps | 99.3% |
| Norma 201 | <<locked>> | 82% | 55,970 psi | 88% | 2608 fps | 100% |
| Norma 202 | <<locked>> | 82% | 56,710 psi | 89% | 2602 fps | 100% |
| Norma 203B | <<locked>> | 84% | 55,245 psi | 87% | 2651 fps | 100% |
| Norma 204 | <<locked>> | 92% | 54,128 psi | 85% | 2690 fps | 98.9% |
| Norma MRPᴾ | <<locked>> | 100% | 56,391 psi | 88% | 2822 fps | 99.9% |
| Norma URP | <<locked>> | 92% | 54,186 psi | 85% | 2684 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 56,086 psi | 88% | 2680 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 51,895 psi | 81% | 2740 fps | 98.2% |
| Ramshot Hunter | <<locked>> | 94% | 56,608 psi | 89% | 2743 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 45,992 psi | 72% | 2618 fps | 98.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,912 psi | 58% | 1654 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 56,898 psi | 89% | 2667 fps | 100% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 57,334 psi | 90% | 2733 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 57,479 psi | 90% | 2762 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 55,361 psi | 87% | 2723 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 54,012 psi | 85% | 2756 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 42,148 psi | 66% | 2641 fps | 98.7% |
| Rottweil R 902 | <<locked>> | 84% | 56,637 psi | 89% | 2608 fps | 100% |
| Rottweil R 903 | <<locked>> | 88% | 56,492 psi | 89% | 2654 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 54,723 psi | 86% | 2671 fps | 98.3% |
| Rottweil R 905 | <<locked>> | 98% | 55,085 psi | 86% | 2726 fps | 99.3% |
| Rottweil R 907 | <<locked>> | 90% | 55,840 psi | 88% | 2654 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 92% | 57,711 psi | 90% | 2674 fps | 100% |
| Shooters World Match Rifle | <<locked>> | 82% | 57,740 psi | 90% | 2635 fps | 100% |
| Shooters World Precision | <<locked>> | 84% | 54,563 psi | 86% | 2598 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 55,347 psi | 87% | 2667 fps | 99.9% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 54,708 psi | 86% | 2667 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 55,912 psi | 88% | 2641 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 56,753 psi | 89% | 2533 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 54,317 psi | 85% | 2497 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 92% | 57,522 psi | 90% | 2631 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 54,607 psi | 86% | 2723 fps | 99.2% |
| Somchem S335 | <<locked>> | 82% | 56,521 psi | 89% | 2533 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 56,623 psi | 89% | 2651 fps | 100% |
| Somchem S361 | <<locked>> | 96% | 56,376 psi | 88% | 2664 fps | 97.8% |
| Somchem S365 | <<locked>> | 96% | 57,276 psi | 90% | 2733 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 55,579 psi | 87% | 2700 fps | 99.7% |
| Vihtavuori N133 | <<locked>> | 82% | 57,319 psi | 90% | 2513 fps | 100% |
| Vihtavuori N135 | <<locked>> | 84% | 56,985 psi | 89% | 2559 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 57,363 psi | 90% | 2579 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 54,331 psi | 85% | 2579 fps | 100% |
| Vihtavuori N160 | <<locked>> | 92% | 56,376 psi | 88% | 2677 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 51,256 psi | 80% | 2625 fps | 99% |
| Vihtavuori N540 | <<locked>> | 84% | 55,477 psi | 87% | 2582 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 55,390 psi | 87% | 2687 fps | 100% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 55,869 psi | 88% | 2743 fps | 100% |
| Vihtavuori N560ᴾ | <<locked>> | 100% | 56,797 psi | 89% | 2818 fps | 98.4% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 44,701 psi | 70% | 2615 fps | 96.2% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 55,985 psi | 88% | 2648 fps | 100% |
| Winchester 760 | <<locked>> | 90% | 54,389 psi | 85% | 2707 fps | 99.8% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 44,962 psi | 70% | 2736 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 82% | 56,014 psi | 88% | 2648 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 55,796 psi | 87% | 2697 fps | 99.2% |
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 2495 | <<locked>> | 80% | 50,546 psi | 79% | 2487 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 48,791 psi | 76% | 2510 fps | 98.8% |
| Accurate 3100 | <<locked>> | 82% | 28,442 psi | 45% | 2198 fps | 95% |
| Accurate 4064 | <<locked>> | 80% | 47,935 psi | 75% | 2497 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 36,521 psi | 57% | 2392 fps | 99.1% |
| Accurate High Country | 73.9 gr | 90% | 40,886 psi | 64% | 2569 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 94% | 44,672 psi | 70% | 2628 fps | 95.2% |
| ADI AR 2206H | <<locked>> | 80% | 53,896 psi | 84% | 2615 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 45,701 psi | 72% | 2484 fps | 100% |
| ADI AR 2209 | <<locked>> | 86% | 38,101 psi | 60% | 2431 fps | 95.5% |
| ADI AR 2213 | <<locked>> | 92% | 41,365 psi | 65% | 2523 fps | 95% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 50,633 psi | 79% | 2690 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 38,218 psi | 60% | 2431 fps | 95.7% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 38,218 psi | 60% | 2431 fps | 95.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 46,209 psi | 72% | 2507 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 49,327 psi | 77% | 2572 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 35,824 psi | 56% | 2402 fps | 99.3% |
| Alliant Reloder-17 | <<locked>> | 80% | 40,698 psi | 64% | 2520 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 37,811 psi | 59% | 2428 fps | 95.6% |
| Alliant Reloder-22 | <<locked>> | 90% | 37,753 psi | 59% | 2470 fps | 95.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 25,976 psi | 41% | 2182 fps | 97.5% |
| Alliant Reloder-25 | <<locked>> | 88% | 29,515 psi | 46% | 2293 fps | 95.9% |
| Alliant Reloder-26 | 67.7 gr | 80% | 27,557 psi | 43% | 2280 fps | 95.9% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 53,780 psi | 84% | 2638 fps | 100% |
| Bofors RP15 | <<locked>> | 92% | 37,260 psi | 58% | 2461 fps | 95.4% |
| Bofors RP3 | <<locked>> | 80% | 46,311 psi | 73% | 2516 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 37,753 psi | 59% | 2470 fps | 95.8% |
| Bofors RP7 | <<locked>> | 80% | 40,770 psi | 64% | 2405 fps | 97.5% |
| Hodgdon H1000 | <<locked>> | 98% | 40,306 psi | 63% | 2497 fps | 95.5% |
| Hodgdon H380 | <<locked>> | 80% | 46,818 psi | 73% | 2533 fps | 99.9% |
| Hodgdon H414 | <<locked>> | 80% | 38,638 psi | 61% | 2438 fps | 97.6% |
| Hodgdon H4350 | <<locked>> | 80% | 41,785 psi | 65% | 2457 fps | 97.1% |
| Hodgdon H4831 | <<locked>> | 92% | 44,353 psi | 70% | 2533 fps | 95.3% |
| Hodgdon H4831 SC | <<locked>> | 92% | 43,395 psi | 68% | 2516 fps | 95% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 33,301 psi | 52% | 2303 fps | 99.6% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 51,198 psi | 80% | 2612 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 37,289 psi | 58% | 2530 fps | 96% |
| Hodgdon Superformance | <<locked>> | 80% | 37,521 psi | 59% | 2448 fps | 96.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,079 psi | 42% | 1440 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 52,170 psi | 82% | 2579 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 48,080 psi | 75% | 2513 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 50,401 psi | 79% | 2546 fps | 99.4% |
| IMR 4350 | <<locked>> | 80% | 36,477 psi | 57% | 2339 fps | 96.3% |
| IMR 4451 Enduron | <<locked>> | 80% | 42,279 psi | 66% | 2434 fps | 98.2% |
| IMR 4831 | <<locked>> | 80% | 35,259 psi | 55% | 2349 fps | 98.9% |
| IMR 4895 | <<locked>> | 80% | 50,618 psi | 79% | 2595 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 90% | 43,569 psi | 68% | 2480 fps | 95.3% |
| IMR 7828 SSC | <<locked>> | 94% | 42,119 psi | 66% | 2552 fps | 95.4% |
| Lovex D073.6 | <<locked>> | 80% | 54,056 psi | 85% | 2589 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 52,881 psi | 83% | 2546 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 48,269 psi | 76% | 2510 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 39,668 psi | 62% | 2385 fps | 98.7% |
| Lovex S070 | <<locked>> | 80% | 37,884 psi | 59% | 2372 fps | 97.5% |
| Lovex S071 | <<locked>> | 88% | 29,588 psi | 46% | 2228 fps | 95.5% |
| Norma 201 | <<locked>> | 80% | 52,431 psi | 82% | 2559 fps | 100% |
| Norma 202 | <<locked>> | 80% | 53,388 psi | 84% | 2559 fps | 100% |
| Norma 203B | <<locked>> | 80% | 48,689 psi | 76% | 2559 fps | 100% |
| Norma 204 | <<locked>> | 82% | 38,479 psi | 60% | 2421 fps | 95.6% |
| Norma MRP | <<locked>> | 84% | 32,169 psi | 50% | 2372 fps | 95.1% |
| Norma URP | <<locked>> | 80% | 36,535 psi | 57% | 2388 fps | 99.1% |
| Ramshot Big Game | <<locked>> | 80% | 49,037 psi | 77% | 2582 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 41,800 psi | 66% | 2559 fps | 95.7% |
| Ramshot Hunter | <<locked>> | 80% | 35,317 psi | 55% | 2379 fps | 97.4% |
| Ramshot Magnum | <<locked>> | 92% | 34,287 psi | 54% | 2382 fps | 95.1% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,543 psi | 43% | 1476 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 46,789 psi | 73% | 2516 fps | 99.4% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 53,374 psi | 84% | 2677 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 43,294 psi | 68% | 2562 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 36,318 psi | 57% | 2411 fps | 98.9% |
| ReloadSwiss RS 70 | 67.1 gr | 80% | 35,404 psi | 55% | 2421 fps | 98.5% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 34,069 psi | 53% | 2451 fps | 95.8% |
| Rottweil R 902 | <<locked>> | 80% | 49,951 psi | 78% | 2516 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 43,526 psi | 68% | 2467 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 42,322 psi | 66% | 2464 fps | 95.6% |
| Rottweil R 905 | <<locked>> | 86% | 36,782 psi | 58% | 2408 fps | 95.5% |
| Rottweil R 907 | <<locked>> | 80% | 40,770 psi | 64% | 2405 fps | 97.5% |
| Shooters World Long Rifle | <<locked>> | 80% | 39,668 psi | 62% | 2385 fps | 98.7% |
| Shooters World Match Rifle | <<locked>> | 80% | 54,056 psi | 85% | 2589 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 48,269 psi | 76% | 2510 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 37,884 psi | 59% | 2372 fps | 97.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 44,759 psi | 70% | 2520 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 52,228 psi | 82% | 2592 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 53,534 psi | 84% | 2493 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 45,194 psi | 71% | 2375 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 38,754 psi | 61% | 2336 fps | 97.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 36,434 psi | 57% | 2405 fps | 95.3% |
| Somchem S335 | <<locked>> | 80% | 53,055 psi | 83% | 2490 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 43,918 psi | 69% | 2467 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 46,180 psi | 72% | 2510 fps | 95.7% |
| Somchem S365 | <<locked>> | 80% | 32,866 psi | 52% | 2346 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 34,983 psi | 55% | 2343 fps | 95.8% |
| Vihtavuori N133 | <<locked>> | 80% | 54,157 psi | 85% | 2477 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 50,444 psi | 79% | 2480 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 50,560 psi | 79% | 2497 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 41,974 psi | 66% | 2402 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 37,985 psi | 60% | 2388 fps | 99.3% |
| Vihtavuori N165 | <<locked>> | 88% | 34,403 psi | 54% | 2323 fps | 95.1% |
| Vihtavuori N540 | <<locked>> | 80% | 48,834 psi | 77% | 2493 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 37,405 psi | 59% | 2392 fps | 99% |
| Vihtavuori N555 | <<locked>> | 80% | 28,631 psi | 45% | 2247 fps | 97.6% |
| Vihtavuori N560 | <<locked>> | 92% | 43,076 psi | 68% | 2589 fps | 95.4% |
| Vihtavuori N565 | <<locked>> | 98% | 41,553 psi | 65% | 2559 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 37,101 psi | 58% | 2359 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 38,798 psi | 61% | 2441 fps | 97.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 22,771 psi | 36% | 2152 fps | 96.4% |
| Winchester StaBALL Match | <<locked>> | 80% | 52,286 psi | 82% | 2598 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 36,738 psi | 58% | 2379 fps | 95.2% |
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 107 powders for .340 Weath. Mag. loaded with the .338 | 250gr | Barnes MRX BT. Alliant Reloder-26 delivers the highest muzzle velocity at 2,861 fps; across all powders the maximum-charge window runs from 1,614 fps to 2,861 fps. Accurate 3100 gives the best case fill at 100 %, and 107 of the 107 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 57–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.338" calls for a 1:14.0 twist; slower twists will usually not stabilise this weight. Accurate 3100, Accurate MAGPRO, ADI AR 2213 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. Alliant Reloder-26, Accurate High Country, ReloadSwiss RS 70 rank at the top here: for .340 Weath. Mag. with the .338 | 250gr | Barnes MRX 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.