Load Specifications
Load data in caliber .338 Lapua Mag. Ackley Improved with .338 | 250gr | TWENTY-NINE ERTP bullet and 82 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Accurate High Country, Hodgdon Retumbo and ReloadSwiss RS 76.
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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You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 27"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 92% | 59,117 psi | 85% | 2822 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 59,944 psi | 86% | 2841 fps | 100% |
| Accurate High Country | <<locked>> | 90% | 61,076 psi | 88% | 2992 fps | 100% |
| Accurate MAGPRO | <<locked>> | 92% | 62,033 psi | 89% | 2999 fps | 99.9% |
| ADI APS 450 | <<locked>> | 82% | 61,308 psi | 88% | 2195 fps | 100% |
| ADI AR 2209 | <<locked>> | 90% | 60,698 psi | 87% | 2913 fps | 100% |
| ADI AR 2213 | <<locked>> | 94% | 62,903 psi | 90% | 2989 fps | 100% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 56,913 psi | 82% | 2904 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 49,429 psi | 71% | 2887 fps | 97.4% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 51,314 psi | 74% | 2871 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 90% | 60,814 psi | 87% | 2910 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 86% | 60,829 psi | 87% | 2890 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 62,323 psi | 90% | 2900 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 90% | 60,089 psi | 86% | 2904 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 92% | 59,001 psi | 85% | 2923 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 94% | 60,727 psi | 87% | 2874 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 98% | 60,640 psi | 87% | 2949 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 90% | 61,859 psi | 89% | 2976 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 54,012 psi | 78% | 2940 fps | 98.4% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 45,455 psi | 65% | 2789 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 59,495 psi | 85% | 2894 fps | 99% |
| Bofors RP15 | <<locked>> | 96% | 62,062 psi | 89% | 2966 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 60,263 psi | 87% | 2969 fps | 100% |
| Bofors RP5 | <<locked>> | 92% | 59,001 psi | 85% | 2923 fps | 100% |
| Bofors RP7 | <<locked>> | 84% | 61,134 psi | 88% | 2838 fps | 100% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 62,830 psi | 90% | 2979 fps | 100% |
| Hodgdon H414 | <<locked>> | 84% | 61,366 psi | 88% | 2900 fps | 100% |
| Hodgdon H4350 | <<locked>> | 82% | 59,770 psi | 86% | 2858 fps | 100% |
| Hodgdon H4831 | <<locked>> | 92% | 62,337 psi | 90% | 2920 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 92% | 60,974 psi | 88% | 2904 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 61,105 psi | 88% | 2808 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 98% | 59,538 psi | 86% | 3041 fps | 100% |
| Hodgdon Superformance | <<locked>> | 84% | 62,671 psi | 90% | 2943 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,449 psi | 54% | 1759 fps | 100% |
| IMR 4350 | <<locked>> | 86% | 59,509 psi | 85% | 2831 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 84% | 62,569 psi | 90% | 2858 fps | 100% |
| IMR 4831 | <<locked>> | 86% | 60,075 psi | 86% | 2831 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 62,526 psi | 90% | 2894 fps | 100% |
| IMR 7828 SSC | <<locked>> | 94% | 61,003 psi | 88% | 2969 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 98% | 60,916 psi | 88% | 2838 fps | 96.3% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 46,775 psi | 67% | 2789 fps | 99.5% |
| Lovex S065 | <<locked>> | 84% | 59,770 psi | 86% | 2802 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 61,815 psi | 89% | 2858 fps | 100% |
| Lovex S071 | <<locked>> | 98% | 60,452 psi | 87% | 2838 fps | 100% |
| Norma 204 | <<locked>> | 86% | 61,017 psi | 88% | 2897 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 47,384 psi | 68% | 2812 fps | 100% |
| Norma MRP | <<locked>> | 90% | 59,263 psi | 85% | 2943 fps | 100% |
| Norma URP | <<locked>> | 86% | 61,757 psi | 89% | 2871 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 62,613 psi | 90% | 2992 fps | 100% |
| Ramshot Hunter | <<locked>> | 86% | 60,742 psi | 87% | 2887 fps | 100% |
| Ramshot Magnum | <<locked>> | 96% | 60,800 psi | 87% | 2920 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,421 psi | 55% | 1801 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 60,162 psi | 86% | 2867 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 62,961 psi | 90% | 2953 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 98% | 60,785 psi | 87% | 3038 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 59,915 psi | 86% | 3009 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 90% | 61,395 psi | 88% | 2881 fps | 100% |
| Rottweil R 905 | <<locked>> | 90% | 59,857 psi | 86% | 2894 fps | 100% |
| Rottweil R 907 | <<locked>> | 84% | 61,134 psi | 88% | 2838 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 84% | 59,770 psi | 86% | 2802 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 61,815 psi | 89% | 2858 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 61,743 psi | 89% | 2677 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 62,758 psi | 90% | 2812 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 90% | 59,437 psi | 85% | 2890 fps | 100% |
| Somchem S355 | <<locked>> | 82% | 62,381 psi | 90% | 2815 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 59,176 psi | 85% | 2822 fps | 99.8% |
| Somchem S365 | <<locked>> | 86% | 59,190 psi | 85% | 2822 fps | 100% |
| Somchem S385 | <<locked>> | 90% | 60,176 psi | 86% | 2861 fps | 100% |
| Vihtavuori N150 | <<locked>> | 82% | 59,857 psi | 86% | 2736 fps | 100% |
| Vihtavuori N160 | <<locked>> | 84% | 59,611 psi | 86% | 2808 fps | 100% |
| Vihtavuori N165 | <<locked>> | 94% | 60,046 psi | 86% | 2844 fps | 100% |
| Vihtavuori N170ᴾ | <<locked>> | 100% | 62,946 psi | 90% | 2930 fps | 98.2% |
| Vihtavuori N550 | <<locked>> | 86% | 62,598 psi | 90% | 2867 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 62,787 psi | 90% | 2900 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 62,758 psi | 90% | 3005 fps | 100% |
| Vihtavuori N565 | <<locked>> | 96% | 59,190 psi | 85% | 2936 fps | 100% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 60,481 psi | 87% | 3005 fps | 99.8% |
| Vihtavuori N570ᴾ | <<locked>> | 100% | 57,246 psi | 82% | 3009 fps | 98.6% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 59,059 psi | 85% | 2762 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 61,554 psi | 88% | 2900 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 94% | 60,220 psi | 87% | 2969 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 60,321 psi | 87% | 2864 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 27"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 39,668 psi | 57% | 2523 fps | 99.9% |
| Accurate 4350 | <<locked>> | 80% | 52,533 psi | 75% | 2743 fps | 100% |
| Accurate High Country | 86.6 gr | 80% | 43,207 psi | 62% | 2700 fps | 98.6% |
| Accurate MAGPRO | <<locked>> | 80% | 40,756 psi | 59% | 2641 fps | 97% |
| ADI APS 450 | <<locked>> | 80% | 59,277 psi | 85% | 2165 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 43,598 psi | 63% | 2644 fps | 99.3% |
| ADI AR 2213 | <<locked>> | 80% | 39,044 psi | 56% | 2589 fps | 97.5% |
| ADI AR 2217 | <<locked>> | 84% | 33,257 psi | 48% | 2451 fps | 95.8% |
| ADI AR 2218 | <<locked>> | 96% | 42,714 psi | 61% | 2746 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 80% | 26,527 psi | 38% | 2306 fps | 95.7% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 44,048 psi | 63% | 2644 fps | 99.3% |
| Alliant Reloder-16 | <<locked>> | 80% | 50,183 psi | 72% | 2746 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 58,117 psi | 83% | 2851 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 43,642 psi | 63% | 2641 fps | 99.3% |
| Alliant Reloder-22 | <<locked>> | 80% | 39,581 psi | 57% | 2598 fps | 98.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 38,363 psi | 55% | 2543 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 33,054 psi | 47% | 2480 fps | 99.6% |
| Alliant Reloder-26 | <<locked>> | 80% | 42,757 psi | 61% | 2697 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 43,120 psi | 62% | 2746 fps | 95.8% |
| Alliant Reloder-50 | <<locked>> | 98% | 42,235 psi | 61% | 2726 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 43,497 psi | 62% | 2618 fps | 95.8% |
| Bofors RP15 | <<locked>> | 80% | 36,869 psi | 53% | 2536 fps | 98% |
| Bofors RP30 | <<locked>> | 80% | 30,589 psi | 44% | 2415 fps | 95% |
| Bofors RP5 | <<locked>> | 80% | 39,581 psi | 57% | 2598 fps | 98.7% |
| Bofors RP7 | <<locked>> | 80% | 53,940 psi | 77% | 2740 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 31,560 psi | 45% | 2408 fps | 95.7% |
| Hodgdon H414 | <<locked>> | 80% | 53,751 psi | 77% | 2795 fps | 100% |
| Hodgdon H4350 | <<locked>> | 80% | 56,072 psi | 81% | 2805 fps | 100% |
| Hodgdon H4831 | <<locked>> | 80% | 41,539 psi | 60% | 2589 fps | 97.5% |
| Hodgdon H4831 SC | <<locked>> | 80% | 40,872 psi | 59% | 2572 fps | 97.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 47,181 psi | 68% | 2621 fps | 100% |
| Hodgdon Retumbo | 83.4 gr | 80% | 32,271 psi | 46% | 2513 fps | 97.4% |
| Hodgdon Superformance | <<locked>> | 80% | 54,201 psi | 78% | 2831 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,210 psi | 41% | 1575 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 49,313 psi | 71% | 2680 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 80% | 55,317 psi | 79% | 2759 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 49,516 psi | 71% | 2687 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 42,888 psi | 62% | 2582 fps | 98% |
| IMR 7828 SSC | <<locked>> | 80% | 37,681 psi | 54% | 2569 fps | 97.2% |
| IMR 7977 Enduron | <<locked>> | 96% | 57,217 psi | 82% | 2782 fps | 95.6% |
| IMR 8133 Enduron | <<locked>> | 88% | 31,343 psi | 45% | 2454 fps | 95.1% |
| Lovex S065 | <<locked>> | 80% | 52,982 psi | 76% | 2710 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 51,387 psi | 74% | 2710 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 34,142 psi | 49% | 2405 fps | 99.2% |
| Norma 204 | <<locked>> | 80% | 49,937 psi | 72% | 2733 fps | 99.8% |
| Norma 217 | <<locked>> | 84% | 27,499 psi | 40% | 2365 fps | 95.7% |
| Norma MRP | <<locked>> | 80% | 41,771 psi | 60% | 2664 fps | 99.8% |
| Norma URP | <<locked>> | 80% | 51,053 psi | 73% | 2726 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 37,362 psi | 54% | 2575 fps | 97.5% |
| Ramshot Hunter | <<locked>> | 80% | 49,937 psi | 72% | 2736 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 33,533 psi | 48% | 2464 fps | 98% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,863 psi | 41% | 1614 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 52,431 psi | 75% | 2762 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 50,850 psi | 73% | 2789 fps | 100% |
| ReloadSwiss RS 76 | 89.3 gr | 80% | 31,343 psi | 45% | 2487 fps | 98.2% |
| ReloadSwiss RS 80 | <<locked>> | 86% | 35,230 psi | 51% | 2566 fps | 95.3% |
| Rottweil R 904 | <<locked>> | 80% | 44,715 psi | 64% | 2618 fps | 98.7% |
| Rottweil R 905 | <<locked>> | 80% | 43,076 psi | 62% | 2625 fps | 99.3% |
| Rottweil R 907 | <<locked>> | 80% | 53,940 psi | 77% | 2740 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 80% | 52,982 psi | 76% | 2710 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 51,387 psi | 74% | 2710 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 58,044 psi | 83% | 2631 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 51,692 psi | 74% | 2661 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 42,728 psi | 61% | 2621 fps | 99.2% |
| Somchem S355 | <<locked>> | 80% | 58,711 psi | 84% | 2769 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 45,498 psi | 65% | 2608 fps | 98.3% |
| Somchem S365 | <<locked>> | 80% | 48,472 psi | 70% | 2680 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 43,627 psi | 63% | 2605 fps | 99.7% |
| Vihtavuori N150 | <<locked>> | 80% | 56,275 psi | 81% | 2690 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 52,475 psi | 75% | 2713 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 38,000 psi | 55% | 2490 fps | 98.7% |
| Vihtavuori N170 | <<locked>> | 92% | 48,051 psi | 69% | 2700 fps | 95.3% |
| Vihtavuori N550 | <<locked>> | 80% | 51,750 psi | 74% | 2723 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 42,699 psi | 61% | 2612 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 41,655 psi | 60% | 2657 fps | 97.8% |
| Vihtavuori N565 | <<locked>> | 80% | 34,389 psi | 49% | 2484 fps | 95.8% |
| Vihtavuori N568 | <<locked>> | 86% | 36,680 psi | 53% | 2582 fps | 95.2% |
| Vihtavuori N570 | <<locked>> | 92% | 42,960 psi | 62% | 2756 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 51,648 psi | 74% | 2667 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 53,911 psi | 77% | 2795 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 35,462 psi | 51% | 2595 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 39,900 psi | 57% | 2536 fps | 98.7% |
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 82 powders for .338 Lapua Mag. Ackley Improved loaded with the .338 | 250gr | TWENTY-NINE ERTP. Hodgdon Retumbo delivers the highest muzzle velocity at 3,041 fps; across all powders the maximum-charge window runs from 1,759 fps to 3,041 fps. ADI AR 2217 gives the best case fill at 100 %, and 82 of the 82 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (480 MPa), the top charges use 54–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.338" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2218, ADI AR 2225 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. Accurate High Country, Hodgdon Retumbo, ReloadSwiss RS 76 rank at the top here: for .338 Lapua Mag. Ackley Improved with the .338 | 250gr | TWENTY-NINE ERTP 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.