Load Specifications
Load data in caliber .338 Lapua Mag. Ackley Improved with .338 | 250gr | Barnes MRX BT bullet and 77 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 IMR 7828 SSC.
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: 27"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 92% | 61,308 psi | 88% | 2867 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 62,004 psi | 89% | 2884 fps | 100% |
| Accurate MAGPRO | <<locked>> | 92% | 61,612 psi | 89% | 3005 fps | 99.8% |
| ADI APS 450 | <<locked>> | 82% | 61,293 psi | 88% | 2221 fps | 100% |
| ADI AR 2209 | <<locked>> | 88% | 59,234 psi | 85% | 2910 fps | 100% |
| ADI AR 2213 | <<locked>> | 92% | 61,612 psi | 89% | 2986 fps | 100% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 59,785 psi | 86% | 2959 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 51,967 psi | 75% | 2956 fps | 98.4% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 54,099 psi | 78% | 2923 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 84% | 59,408 psi | 85% | 2887 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 90% | 62,482 psi | 90% | 2949 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 92% | 61,656 psi | 89% | 2976 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 92% | 59,364 psi | 85% | 2871 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 96% | 59,553 psi | 86% | 2946 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 88% | 60,582 psi | 87% | 2969 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 57,319 psi | 82% | 3002 fps | 99.1% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 48,341 psi | 69% | 2851 fps | 97.1% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 61,946 psi | 89% | 2946 fps | 99.5% |
| Bofors RP15 | <<locked>> | 94% | 60,742 psi | 87% | 2963 fps | 100% |
| Bofors RP30 | <<locked>> | 98% | 59,176 psi | 85% | 2969 fps | 100% |
| Bofors RP5 | <<locked>> | 92% | 61,656 psi | 89% | 2976 fps | 100% |
| Bofors RP7 | <<locked>> | 84% | 62,975 psi | 90% | 2884 fps | 100% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 61,583 psi | 88% | 2979 fps | 100% |
| Hodgdon H4350 | <<locked>> | 84% | 60,321 psi | 87% | 2884 fps | 100% |
| Hodgdon H4831 | <<locked>> | 94% | 60,205 psi | 86% | 2913 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 90% | 59,480 psi | 85% | 2904 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 59,350 psi | 85% | 2805 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 58,726 psi | 84% | 3045 fps | 100% |
| Hodgdon Superformance | <<locked>> | 82% | 60,742 psi | 87% | 2936 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,507 psi | 54% | 1785 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 61,902 psi | 89% | 2848 fps | 100% |
| IMR 4350 | <<locked>> | 86% | 61,569 psi | 88% | 2874 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 82% | 60,524 psi | 87% | 2851 fps | 100% |
| IMR 4831 | <<locked>> | 88% | 59,843 psi | 86% | 2844 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 90% | 60,872 psi | 87% | 2894 fps | 100% |
| IMR 7828 SSC | <<locked>> | 90% | 59,814 psi | 86% | 2969 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 96% | 59,408 psi | 85% | 2841 fps | 96.5% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 49,356 psi | 71% | 2841 fps | 99.8% |
| Lovex S065 | <<locked>> | 84% | 61,511 psi | 88% | 2844 fps | 100% |
| Lovex S070 | <<locked>> | 84% | 59,901 psi | 86% | 2851 fps | 100% |
| Lovex S071 | <<locked>> | 98% | 62,859 psi | 90% | 2884 fps | 100% |
| Norma 204 | <<locked>> | 84% | 59,161 psi | 85% | 2890 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 50,140 psi | 72% | 2864 fps | 100% |
| Norma MRP | <<locked>> | 90% | 61,989 psi | 89% | 2992 fps | 100% |
| Norma URP | <<locked>> | 84% | 59,988 psi | 86% | 2864 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 60,234 psi | 87% | 2976 fps | 100% |
| Ramshot Hunter | <<locked>> | 84% | 58,987 psi | 85% | 2881 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 61,525 psi | 88% | 2943 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,537 psi | 55% | 1831 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 62,366 psi | 90% | 2910 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 84% | 61,235 psi | 88% | 2943 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 59,756 psi | 86% | 3031 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 58,827 psi | 85% | 3005 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 59,857 psi | 86% | 2877 fps | 100% |
| Rottweil R 905 | <<locked>> | 90% | 62,381 psi | 90% | 2943 fps | 100% |
| Rottweil R 907 | <<locked>> | 84% | 62,975 psi | 90% | 2884 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 84% | 61,511 psi | 88% | 2844 fps | 100% |
| Shooters World SW4350 | <<locked>> | 84% | 59,901 psi | 86% | 2851 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 84% | 60,553 psi | 87% | 2805 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 90% | 61,960 psi | 89% | 2940 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 61,337 psi | 88% | 2874 fps | 100% |
| Somchem S365 | <<locked>> | 86% | 61,583 psi | 88% | 2864 fps | 100% |
| Somchem S385 | <<locked>> | 90% | 62,540 psi | 90% | 2907 fps | 100% |
| Unknown powder | <<locked>> | 82% | 59,944 psi | 86% | 2867 fps | 100% |
| Vihtavuori N150 | <<locked>> | 86% | 62,569 psi | 90% | 2789 fps | 100% |
| Vihtavuori N160 | <<locked>> | 82% | 60,292 psi | 87% | 2831 fps | 100% |
| Vihtavuori N165 | <<locked>> | 94% | 60,452 psi | 87% | 2867 fps | 100% |
| Vihtavuori N170ᴾ | <<locked>> | 100% | 55,027 psi | 79% | 2838 fps | 97.3% |
| Vihtavuori N550 | <<locked>> | 82% | 60,829 psi | 87% | 2881 fps | 100% |
| Vihtavuori N555 | <<locked>> | 90% | 61,308 psi | 88% | 2897 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 62,207 psi | 89% | 3015 fps | 100% |
| Vihtavuori N565 | <<locked>> | 96% | 61,917 psi | 89% | 2989 fps | 100% |
| Vihtavuori N568 | <<locked>> | 98% | 59,437 psi | 85% | 3005 fps | 99.9% |
| Vihtavuori N570ᴾ | <<locked>> | 100% | 61,409 psi | 88% | 3074 fps | 99.3% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 61,308 psi | 88% | 2802 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 92% | 59,466 psi | 85% | 2966 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 60,147 psi | 86% | 2877 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% | 40,727 psi | 59% | 2556 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 54,085 psi | 78% | 2782 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 40,161 psi | 58% | 2635 fps | 96.4% |
| ADI APS 450 | <<locked>> | 80% | 59,364 psi | 85% | 2195 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 45,121 psi | 65% | 2687 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 80% | 40,451 psi | 58% | 2635 fps | 98.2% |
| ADI AR 2217 | <<locked>> | 82% | 31,981 psi | 46% | 2434 fps | 95.6% |
| ADI AR 2218 | <<locked>> | 94% | 41,684 psi | 60% | 2743 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 80% | 27,209 psi | 39% | 2346 fps | 96.5% |
| Alliant Reloder-16 | <<locked>> | 80% | 52,040 psi | 75% | 2785 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 45,063 psi | 65% | 2684 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 80% | 41,046 psi | 59% | 2638 fps | 99.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 39,740 psi | 57% | 2579 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 34,185 psi | 49% | 2520 fps | 99.8% |
| Alliant Reloder-26 | <<locked>> | 80% | 44,730 psi | 64% | 2740 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 42,250 psi | 61% | 2740 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 96% | 41,379 psi | 59% | 2717 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 42,134 psi | 61% | 2612 fps | 95.9% |
| Bofors RP15 | <<locked>> | 80% | 38,159 psi | 55% | 2579 fps | 98.5% |
| Bofors RP30 | <<locked>> | 80% | 31,618 psi | 45% | 2451 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 41,046 psi | 59% | 2638 fps | 99.2% |
| Bofors RP7 | <<locked>> | 80% | 55,521 psi | 80% | 2782 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 30,734 psi | 44% | 2405 fps | 95.7% |
| Hodgdon H4350 | <<locked>> | 80% | 53,171 psi | 76% | 2779 fps | 100% |
| Hodgdon H4831 | <<locked>> | 80% | 37,898 psi | 54% | 2526 fps | 96.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 42,308 psi | 61% | 2618 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 48,907 psi | 70% | 2664 fps | 100% |
| Hodgdon Retumbo | 88.4 gr | 80% | 33,417 psi | 48% | 2559 fps | 98.2% |
| Hodgdon Superformance | <<locked>> | 80% | 56,507 psi | 81% | 2877 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,108 psi | 40% | 1594 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 58,233 psi | 84% | 2799 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 50,836 psi | 73% | 2723 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 80% | 56,985 psi | 82% | 2802 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 46,485 psi | 67% | 2651 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 44,179 psi | 63% | 2625 fps | 98.5% |
| IMR 7828 SSC | 90.3 gr | 80% | 41,713 psi | 60% | 2671 fps | 98.5% |
| IMR 7977 Enduron | <<locked>> | 94% | 55,608 psi | 80% | 2785 fps | 95.7% |
| IMR 8133 Enduron | <<locked>> | 86% | 30,371 psi | 44% | 2438 fps | 95% |
| Lovex S065 | <<locked>> | 80% | 54,331 psi | 78% | 2746 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 52,837 psi | 76% | 2749 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 34,954 psi | 50% | 2438 fps | 99.5% |
| Norma 204 | <<locked>> | 80% | 51,648 psi | 74% | 2779 fps | 100% |
| Norma 217 | <<locked>> | 82% | 26,513 psi | 38% | 2343 fps | 95.4% |
| Norma MRP | <<locked>> | 80% | 43,511 psi | 63% | 2707 fps | 100% |
| Norma URP | <<locked>> | 80% | 52,736 psi | 76% | 2766 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 43,961 psi | 63% | 2723 fps | 99.2% |
| Ramshot Hunter | <<locked>> | 80% | 51,648 psi | 74% | 2776 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 38,479 psi | 55% | 2585 fps | 99.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,848 psi | 41% | 1637 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 54,375 psi | 78% | 2805 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 53,113 psi | 76% | 2835 fps | 100% |
| ReloadSwiss RS 76 | 94.6 gr | 80% | 32,460 psi | 47% | 2530 fps | 98.8% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 34,287 psi | 49% | 2549 fps | 95.2% |
| Rottweil R 904 | <<locked>> | 80% | 46,137 psi | 66% | 2664 fps | 99.2% |
| Rottweil R 905 | <<locked>> | 80% | 44,657 psi | 64% | 2674 fps | 99.6% |
| Rottweil R 907 | <<locked>> | 80% | 55,521 psi | 80% | 2782 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 80% | 54,331 psi | 78% | 2746 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 52,837 psi | 76% | 2749 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 53,171 psi | 76% | 2703 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 44,324 psi | 64% | 2667 fps | 99.6% |
| Somchem S361 | <<locked>> | 80% | 46,978 psi | 67% | 2654 fps | 98.8% |
| Somchem S365 | <<locked>> | 80% | 50,241 psi | 72% | 2717 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 44,962 psi | 65% | 2644 fps | 99.9% |
| Unknown powder | <<locked>> | 80% | 56,144 psi | 81% | 2815 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 52,083 psi | 75% | 2654 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 56,318 psi | 81% | 2782 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 38,087 psi | 55% | 2507 fps | 98.9% |
| Vihtavuori N170 | <<locked>> | 94% | 45,324 psi | 65% | 2671 fps | 95% |
| Vihtavuori N550 | <<locked>> | 80% | 56,898 psi | 82% | 2828 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 44,135 psi | 63% | 2651 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 41,104 psi | 59% | 2661 fps | 97.9% |
| Vihtavuori N565 | <<locked>> | 80% | 35,549 psi | 51% | 2523 fps | 96.5% |
| Vihtavuori N568 | <<locked>> | 84% | 35,636 psi | 51% | 2569 fps | 95.1% |
| Vihtavuori N570 | <<locked>> | 90% | 42,438 psi | 61% | 2749 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 53,476 psi | 77% | 2707 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 37,391 psi | 54% | 2631 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 45,107 psi | 65% | 2651 fps | 99.6% |
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 84 powders for .338 Lapua Mag. Ackley Improved loaded with the .338 | 250gr | Barnes MRX BT. Vihtavuori N570 delivers the highest muzzle velocity at 3,074 fps; across all powders the maximum-charge window runs from 1,785 fps to 3,074 fps. Accurate 8700 gives the best case fill at 100 %, and 84 of the 84 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 1:14.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, ADI AR 2217, ADI AR 2218 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, IMR 7828 SSC rank at the top here: for .338 Lapua Mag. Ackley Improved with the .338 | 250gr | Barnes MRX BT they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 8700, Ramshot LRT, SNPE Vectan SP 13 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.