Load Specifications
Load data in caliber .338 Lapua Mag. Ackley Improved with .338 | 260gr | Peregrine Glider GRM bullet and 87 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 Winchester StaBALL HD.
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 2700 | <<locked>> | 82% | 61,467 psi | 88% | 2749 fps | 100% |
| Accurate 3100 | <<locked>> | 94% | 62,685 psi | 90% | 2818 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 59,611 psi | 86% | 2785 fps | 100% |
| Accurate MAGPRO | <<locked>> | 94% | 62,903 psi | 90% | 2956 fps | 99.9% |
| ADI APS 450 | <<locked>> | 82% | 61,206 psi | 88% | 2149 fps | 100% |
| ADI AR 2208 | <<locked>> | 82% | 62,990 psi | 90% | 2776 fps | 100% |
| ADI AR 2209 | <<locked>> | 90% | 60,698 psi | 87% | 2864 fps | 100% |
| ADI AR 2213 | <<locked>> | 94% | 62,917 psi | 90% | 2936 fps | 100% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 56,681 psi | 81% | 2851 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 49,037 psi | 70% | 2841 fps | 97.8% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 51,039 psi | 73% | 2818 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 90% | 60,742 psi | 87% | 2858 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 86% | 60,887 psi | 87% | 2838 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 62,178 psi | 89% | 2848 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 90% | 60,017 psi | 86% | 2851 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 94% | 62,845 psi | 90% | 2923 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 94% | 60,437 psi | 87% | 2818 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 98% | 60,394 psi | 87% | 2894 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 90% | 61,670 psi | 89% | 2923 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 53,693 psi | 77% | 2890 fps | 98.6% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 45,005 psi | 65% | 2740 fps | 96.3% |
| Baschieri & Pellagri 109 | <<locked>> | 94% | 59,408 psi | 85% | 2848 fps | 99.2% |
| Bofors RP15 | <<locked>> | 96% | 61,902 psi | 89% | 2910 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 59,944 psi | 86% | 2917 fps | 100% |
| Bofors RP5 | <<locked>> | 94% | 62,845 psi | 90% | 2923 fps | 100% |
| Bofors RP7 | <<locked>> | 84% | 61,003 psi | 88% | 2789 fps | 100% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 58,363 psi | 84% | 2871 fps | 100% |
| Hodgdon H414 | <<locked>> | 82% | 62,178 psi | 89% | 2858 fps | 100% |
| Hodgdon H4350 | <<locked>> | 86% | 62,018 psi | 89% | 2835 fps | 100% |
| Hodgdon H4831 | <<locked>> | 96% | 61,598 psi | 88% | 2864 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 92% | 60,988 psi | 88% | 2854 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 60,872 psi | 87% | 2756 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 98% | 59,379 psi | 85% | 2989 fps | 100% |
| Hodgdon Superformance | <<locked>> | 84% | 62,511 psi | 90% | 2890 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,405 psi | 54% | 1722 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 61,917 psi | 89% | 2749 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 59,973 psi | 86% | 2749 fps | 100% |
| IMR 4350 | <<locked>> | 86% | 59,350 psi | 85% | 2779 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 84% | 62,381 psi | 90% | 2805 fps | 100% |
| IMR 4831 | <<locked>> | 90% | 61,264 psi | 88% | 2795 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 62,352 psi | 90% | 2844 fps | 100% |
| IMR 7828 SSC | <<locked>> | 92% | 61,134 psi | 88% | 2920 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 98% | 60,858 psi | 87% | 2792 fps | 96.7% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 46,470 psi | 67% | 2740 fps | 99.6% |
| Lovex S065 | <<locked>> | 84% | 59,509 psi | 85% | 2749 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 61,482 psi | 88% | 2802 fps | 100% |
| Lovex S071 | <<locked>> | 98% | 59,872 psi | 86% | 2782 fps | 100% |
| Norma 204 | <<locked>> | 86% | 60,959 psi | 88% | 2844 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 47,108 psi | 68% | 2762 fps | 100% |
| Norma MRP | <<locked>> | 90% | 59,016 psi | 85% | 2890 fps | 100% |
| Norma URP | <<locked>> | 86% | 61,511 psi | 88% | 2815 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 61,554 psi | 88% | 2930 fps | 100% |
| Ramshot Hunter | <<locked>> | 86% | 60,597 psi | 87% | 2835 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 58,117 psi | 83% | 2838 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,363 psi | 55% | 1765 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 59,886 psi | 86% | 2812 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 62,787 psi | 90% | 2897 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 98% | 60,524 psi | 87% | 2982 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 59,654 psi | 86% | 2956 fps | 100% |
| Rottweil R 903 | <<locked>> | 82% | 62,801 psi | 90% | 2769 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 61,322 psi | 88% | 2831 fps | 100% |
| Rottweil R 905 | <<locked>> | 90% | 59,741 psi | 86% | 2841 fps | 100% |
| Rottweil R 907 | <<locked>> | 84% | 61,003 psi | 88% | 2789 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 84% | 59,509 psi | 85% | 2749 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 61,482 psi | 88% | 2802 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 61,525 psi | 88% | 2625 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 62,482 psi | 90% | 2759 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 90% | 59,306 psi | 85% | 2838 fps | 100% |
| Somchem S355 | <<locked>> | 82% | 62,091 psi | 89% | 2759 fps | 100% |
| Somchem S361 | <<locked>> | 88% | 58,943 psi | 85% | 2772 fps | 99.9% |
| Somchem S365 | <<locked>> | 86% | 58,914 psi | 85% | 2769 fps | 100% |
| Somchem S385 | <<locked>> | 90% | 59,959 psi | 86% | 2808 fps | 100% |
| Unknown powder | <<locked>> | 84% | 61,728 psi | 89% | 2822 fps | 100% |
| Vihtavuori N150 | <<locked>> | 86% | 60,423 psi | 87% | 2697 fps | 100% |
| Vihtavuori N160 | <<locked>> | 84% | 61,946 psi | 89% | 2782 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 61,772 psi | 89% | 2818 fps | 100% |
| Vihtavuori N170ᴾ | <<locked>> | 100% | 52,402 psi | 75% | 2733 fps | 96.7% |
| Vihtavuori N550 | <<locked>> | 84% | 62,453 psi | 90% | 2831 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 62,468 psi | 90% | 2844 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 59,306 psi | 85% | 2910 fps | 100% |
| Vihtavuori N565 | <<locked>> | 98% | 62,859 psi | 90% | 2936 fps | 100% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 60,336 psi | 87% | 2956 fps | 99.9% |
| Vihtavuori N570ᴾ | <<locked>> | 100% | 57,725 psi | 83% | 2959 fps | 98.9% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 59,001 psi | 85% | 2713 fps | 100% |
| Winchester 760 | <<locked>> | 82% | 62,178 psi | 89% | 2858 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 94% | 60,118 psi | 86% | 2913 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 61,728 psi | 89% | 2831 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 2700 | <<locked>> | 80% | 57,450 psi | 83% | 2697 fps | 100% |
| Accurate 3100 | <<locked>> | 80% | 38,986 psi | 56% | 2467 fps | 99.9% |
| Accurate 4350 | <<locked>> | 80% | 51,996 psi | 75% | 2687 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 38,116 psi | 55% | 2539 fps | 95.8% |
| ADI APS 450 | <<locked>> | 80% | 59,321 psi | 85% | 2123 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 59,205 psi | 85% | 2730 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 43,323 psi | 62% | 2595 fps | 99.4% |
| ADI AR 2213 | <<locked>> | 80% | 38,595 psi | 55% | 2539 fps | 97.8% |
| ADI AR 2217 | <<locked>> | 82% | 30,618 psi | 44% | 2346 fps | 95% |
| ADI AR 2218 | <<locked>> | 96% | 42,467 psi | 61% | 2703 fps | 95.6% |
| ADI AR 2225 | <<locked>> | 80% | 25,947 psi | 37% | 2257 fps | 95.8% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 43,787 psi | 63% | 2598 fps | 99.5% |
| Alliant Reloder-16 | <<locked>> | 80% | 49,980 psi | 72% | 2694 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 58,059 psi | 83% | 2799 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 43,337 psi | 62% | 2592 fps | 99.4% |
| Alliant Reloder-22 | <<locked>> | 80% | 39,073 psi | 56% | 2543 fps | 98.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 37,913 psi | 54% | 2490 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 32,590 psi | 47% | 2431 fps | 99.7% |
| Alliant Reloder-26 | <<locked>> | 80% | 42,293 psi | 61% | 2644 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 39,653 psi | 57% | 2631 fps | 95.1% |
| Alliant Reloder-50 | <<locked>> | 98% | 41,669 psi | 60% | 2674 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 40,683 psi | 58% | 2520 fps | 95.3% |
| Bofors RP15 | <<locked>> | 80% | 36,434 psi | 52% | 2487 fps | 98.2% |
| Bofors RP30 | <<locked>> | 80% | 30,023 psi | 43% | 2362 fps | 95.2% |
| Bofors RP5 | <<locked>> | 80% | 39,073 psi | 56% | 2543 fps | 98.9% |
| Bofors RP7 | <<locked>> | 80% | 53,635 psi | 77% | 2687 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 29,399 psi | 42% | 2313 fps | 95.1% |
| Hodgdon H414 | <<locked>> | 80% | 58,175 psi | 84% | 2805 fps | 100% |
| Hodgdon H4350 | <<locked>> | 80% | 51,401 psi | 74% | 2687 fps | 100% |
| Hodgdon H4831 | <<locked>> | 80% | 36,332 psi | 52% | 2438 fps | 96.4% |
| Hodgdon H4831 SC | <<locked>> | 80% | 40,451 psi | 58% | 2523 fps | 97.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 46,963 psi | 67% | 2575 fps | 100% |
| Hodgdon Retumbo | 82.4 gr | 80% | 31,821 psi | 46% | 2464 fps | 97.7% |
| Hodgdon Superformance | <<locked>> | 80% | 54,027 psi | 78% | 2782 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,036 psi | 40% | 1539 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 58,334 psi | 84% | 2707 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 56,550 psi | 81% | 2707 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 49,066 psi | 70% | 2631 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 80% | 55,172 psi | 79% | 2710 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 44,715 psi | 64% | 2562 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 42,627 psi | 61% | 2533 fps | 98.2% |
| IMR 7828 SSC | <<locked>> | 80% | 39,827 psi | 57% | 2575 fps | 98.2% |
| IMR 7977 Enduron | <<locked>> | 94% | 53,359 psi | 77% | 2684 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 88% | 30,763 psi | 44% | 2402 fps | 95.4% |
| Lovex S065 | <<locked>> | 80% | 52,576 psi | 76% | 2657 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 50,995 psi | 73% | 2657 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 33,446 psi | 48% | 2352 fps | 99.3% |
| Norma 204 | <<locked>> | 80% | 49,603 psi | 71% | 2684 fps | 99.9% |
| Norma 217 | <<locked>> | 84% | 26,789 psi | 38% | 2310 fps | 95.8% |
| Norma MRP | <<locked>> | 80% | 41,307 psi | 59% | 2612 fps | 99.8% |
| Norma URP | <<locked>> | 80% | 50,734 psi | 73% | 2674 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 41,713 psi | 60% | 2625 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 80% | 49,559 psi | 71% | 2684 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 36,405 psi | 52% | 2490 fps | 99% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,674 psi | 41% | 1578 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 52,170 psi | 75% | 2710 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 50,647 psi | 73% | 2736 fps | 100% |
| ReloadSwiss RS 76 | 88.2 gr | 80% | 30,792 psi | 44% | 2438 fps | 98.4% |
| ReloadSwiss RS 80 | <<locked>> | 86% | 34,780 psi | 50% | 2516 fps | 95.6% |
| Rottweil R 903 | <<locked>> | 80% | 58,958 psi | 85% | 2723 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 44,396 psi | 64% | 2572 fps | 98.9% |
| Rottweil R 905 | <<locked>> | 80% | 42,670 psi | 61% | 2579 fps | 99.4% |
| Rottweil R 907 | <<locked>> | 80% | 53,635 psi | 77% | 2687 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 80% | 52,576 psi | 76% | 2657 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 50,995 psi | 73% | 2657 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 57,972 psi | 83% | 2582 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 51,329 psi | 74% | 2612 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 42,337 psi | 61% | 2572 fps | 99.4% |
| Somchem S355 | <<locked>> | 80% | 58,349 psi | 84% | 2717 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 45,107 psi | 65% | 2559 fps | 98.5% |
| Somchem S365 | <<locked>> | 80% | 48,095 psi | 69% | 2628 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 43,047 psi | 62% | 2552 fps | 99.8% |
| Unknown powder | <<locked>> | 80% | 54,157 psi | 78% | 2723 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 50,227 psi | 72% | 2566 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 54,186 psi | 78% | 2687 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 36,463 psi | 52% | 2418 fps | 98.7% |
| Vihtavuori N170 | <<locked>> | 96% | 46,122 psi | 66% | 2628 fps | 95.2% |
| Vihtavuori N550 | <<locked>> | 80% | 54,781 psi | 79% | 2733 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 42,221 psi | 61% | 2559 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 39,189 psi | 56% | 2566 fps | 97.5% |
| Vihtavuori N565 | <<locked>> | 80% | 33,808 psi | 49% | 2431 fps | 96% |
| Vihtavuori N568 | <<locked>> | 86% | 36,245 psi | 52% | 2533 fps | 95.5% |
| Vihtavuori N570 | <<locked>> | 92% | 43,047 psi | 62% | 2707 fps | 95.8% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 51,401 psi | 74% | 2618 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 58,175 psi | 84% | 2805 fps | 100% |
| Winchester StaBALL HD | 84.6 gr | 80% | 34,940 psi | 50% | 2539 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 43,163 psi | 62% | 2559 fps | 99.4% |
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 87 powders for .338 Lapua Mag. Ackley Improved loaded with the .338 | 260gr | Peregrine Glider GRM. Hodgdon Retumbo delivers the highest muzzle velocity at 2,989 fps; across all powders the maximum-charge window runs from 1,722 fps to 2,989 fps. ADI AR 2217 gives the best case fill at 100 %, and 87 of the 87 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 260.0 gr projectile in 0.338" calls for a 1:10.0 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. Hodgdon Retumbo, ReloadSwiss RS 76, Winchester StaBALL HD rank at the top here: for .338 Lapua Mag. Ackley Improved with the .338 | 260gr | Peregrine Glider GRM 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.