Load Specifications
Load data in caliber .338 Lapua Mag. Ackley Improved with .338 | 206gr | Peregrine VRG-2 bullet and 97 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N560, Accurate MAGPRO and Norma MRP.
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>> | 84% | 59,480 psi | 85% | 3031 fps | 100% |
| Accurate 3100 | <<locked>> | 96% | 59,190 psi | 85% | 3091 fps | 100% |
| Accurate 4064 | <<locked>> | 82% | 61,598 psi | 88% | 3035 fps | 100% |
| Accurate 4350 | <<locked>> | 88% | 60,408 psi | 87% | 3127 fps | 100% |
| Accurate MAGPRO | <<locked>> | 96% | 58,987 psi | 85% | 3209 fps | 98.5% |
| ADI APS 450 | <<locked>> | 82% | 60,887 psi | 87% | 2411 fps | 100% |
| ADI AR 2208 | <<locked>> | 84% | 61,032 psi | 88% | 3081 fps | 100% |
| ADI AR 2209 | <<locked>> | 94% | 61,554 psi | 88% | 3196 fps | 100% |
| ADI AR 2213 | <<locked>> | 96% | 59,437 psi | 85% | 3209 fps | 99.5% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 49,588 psi | 71% | 3035 fps | 98.6% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 44,222 psi | 64% | 2992 fps | 99.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 62,569 psi | 90% | 3100 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 62,598 psi | 90% | 3130 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 61,496 psi | 88% | 3186 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 84% | 58,900 psi | 85% | 3146 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 60,872 psi | 87% | 3182 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 96% | 59,263 psi | 85% | 3199 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 98% | 60,437 psi | 87% | 3153 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 56,086 psi | 81% | 3166 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 94% | 61,815 psi | 89% | 3261 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 98% | 60,959 psi | 88% | 3159 fps | 97.9% |
| Bofors RP15ᴾ | <<locked>> | 100% | 62,076 psi | 89% | 3235 fps | 100% |
| Bofors RP3 | <<locked>> | 82% | 59,988 psi | 86% | 3071 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 51,938 psi | 75% | 3107 fps | 99.1% |
| Bofors RP5 | <<locked>> | 96% | 59,263 psi | 85% | 3199 fps | 99.9% |
| Bofors RP7 | <<locked>> | 88% | 62,540 psi | 90% | 3130 fps | 100% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 51,010 psi | 73% | 3061 fps | 99.2% |
| Hodgdon H380 | <<locked>> | 82% | 59,930 psi | 86% | 3094 fps | 100% |
| Hodgdon H414 | <<locked>> | 84% | 59,495 psi | 85% | 3150 fps | 100% |
| Hodgdon H4350 | <<locked>> | 88% | 59,379 psi | 85% | 3120 fps | 99.9% |
| Hodgdon H4831ᴾ | <<locked>> | 100% | 62,337 psi | 90% | 3182 fps | 99.4% |
| Hodgdon H4831 SC | <<locked>> | 96% | 62,134 psi | 89% | 3179 fps | 99.4% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 61,685 psi | 89% | 3094 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 62,221 psi | 89% | 3127 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 54,969 psi | 79% | 3245 fps | 100% |
| Hodgdon Superformance | <<locked>> | 86% | 59,306 psi | 85% | 3173 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,985 psi | 53% | 1942 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 60,495 psi | 87% | 3074 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 59,843 psi | 86% | 3054 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 86% | 61,902 psi | 89% | 3100 fps | 100% |
| IMR 4350 | <<locked>> | 90% | 60,655 psi | 87% | 3114 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 86% | 60,321 psi | 87% | 3097 fps | 100% |
| IMR 4831 | <<locked>> | 94% | 61,917 psi | 89% | 3130 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 59,857 psi | 86% | 3117 fps | 99.2% |
| IMR 7828 SSC | <<locked>> | 96% | 61,685 psi | 89% | 3248 fps | 99.7% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 39,508 psi | 57% | 2881 fps | 96.3% |
| Lovex S062 | <<locked>> | 82% | 60,742 psi | 87% | 3048 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 60,843 psi | 87% | 3091 fps | 100% |
| Lovex S070 | <<locked>> | 90% | 62,888 psi | 90% | 3146 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 56,246 psi | 81% | 3051 fps | 100% |
| Norma 203B | <<locked>> | 82% | 61,888 psi | 89% | 3114 fps | 100% |
| Norma 204 | <<locked>> | 90% | 62,250 psi | 89% | 3182 fps | 99.9% |
| Norma 217ᴾ | <<locked>> | 100% | 39,566 psi | 57% | 2907 fps | 98.5% |
| Norma MRP | <<locked>> | 94% | 59,321 psi | 85% | 3219 fps | 100% |
| Norma URP | <<locked>> | 90% | 62,555 psi | 90% | 3163 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 62,047 psi | 89% | 3261 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 90% | 61,525 psi | 88% | 3173 fps | 100% |
| Ramshot Magnum | <<locked>> | 96% | 58,827 psi | 85% | 3163 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,753 psi | 54% | 1985 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 59,698 psi | 86% | 3084 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 62,874 psi | 90% | 3186 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 60,626 psi | 87% | 3150 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 88% | 59,306 psi | 85% | 3189 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 55,912 psi | 80% | 3241 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 50,734 psi | 73% | 3120 fps | 97.9% |
| Rottweil R 902 | <<locked>> | 82% | 62,410 psi | 90% | 3054 fps | 100% |
| Rottweil R 903 | <<locked>> | 84% | 60,220 psi | 87% | 3068 fps | 100% |
| Rottweil R 904 | <<locked>> | 94% | 62,526 psi | 90% | 3159 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 94% | 60,394 psi | 87% | 3169 fps | 100% |
| Rottweil R 907 | <<locked>> | 88% | 62,540 psi | 90% | 3130 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 88% | 60,843 psi | 87% | 3091 fps | 100% |
| Shooters World Precision | <<locked>> | 82% | 60,742 psi | 87% | 3048 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 62,888 psi | 90% | 3146 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 62,091 psi | 89% | 3130 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 59,814 psi | 86% | 2927 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 60,365 psi | 87% | 3045 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 59,944 psi | 86% | 3166 fps | 99.9% |
| Somchem S355 | <<locked>> | 84% | 59,712 psi | 86% | 3061 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 60,553 psi | 87% | 3094 fps | 99.2% |
| Somchem S365 | <<locked>> | 90% | 59,263 psi | 85% | 3107 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 60,829 psi | 87% | 3136 fps | 100% |
| Unknown powder | <<locked>> | 88% | 62,903 psi | 90% | 3169 fps | 100% |
| Vihtavuori N133 | <<locked>> | 82% | 62,134 psi | 89% | 2943 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 62,671 psi | 90% | 3015 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 61,670 psi | 89% | 3038 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 59,176 psi | 85% | 3074 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 62,439 psi | 90% | 3140 fps | 100% |
| Vihtavuori N540 | <<locked>> | 82% | 62,439 psi | 90% | 3045 fps | 100% |
| Vihtavuori N550 | <<locked>> | 86% | 59,683 psi | 86% | 3127 fps | 100% |
| Vihtavuori N555 | <<locked>> | 96% | 62,584 psi | 90% | 3179 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 59,640 psi | 86% | 3232 fps | 99.4% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 58,798 psi | 84% | 3189 fps | 99.4% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 51,808 psi | 74% | 3127 fps | 97.6% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 60,481 psi | 87% | 3048 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 59,495 psi | 85% | 3150 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 98% | 59,030 psi | 85% | 3248 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 58,769 psi | 84% | 3100 fps | 99.9% |
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% | 52,054 psi | 75% | 2920 fps | 99.7% |
| Accurate 3100 | <<locked>> | 80% | 33,765 psi | 49% | 2625 fps | 97.6% |
| Accurate 4064 | <<locked>> | 80% | 57,653 psi | 83% | 2982 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 45,614 psi | 66% | 2897 fps | 100% |
| Accurate MAGPRO | 101.3 gr | 88% | 44,121 psi | 63% | 2940 fps | 95.2% |
| ADI APS 450 | <<locked>> | 80% | 58,929 psi | 85% | 2385 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 53,853 psi | 77% | 2979 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 38,218 psi | 55% | 2769 fps | 96.4% |
| ADI AR 2213 | <<locked>> | 84% | 39,015 psi | 56% | 2818 fps | 95.3% |
| ADI AR 2217 | <<locked>> | 92% | 37,623 psi | 54% | 2776 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 90% | 31,560 psi | 45% | 2667 fps | 95.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 55,071 psi | 79% | 2999 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 58,639 psi | 84% | 3074 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 44,005 psi | 63% | 2910 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 51,068 psi | 73% | 3031 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 38,174 psi | 55% | 2762 fps | 96.5% |
| Alliant Reloder-22 | <<locked>> | 80% | 33,953 psi | 49% | 2697 fps | 95% |
| Alliant Reloder-23 | <<locked>> | 80% | 32,561 psi | 47% | 2661 fps | 99.8% |
| Alliant Reloder-25 | <<locked>> | 80% | 28,355 psi | 41% | 2562 fps | 96.1% |
| Alliant Reloder-26 | <<locked>> | 80% | 35,824 psi | 51% | 2805 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 50,357 psi | 72% | 2979 fps | 95.6% |
| Bofors RP15 | <<locked>> | 84% | 36,245 psi | 52% | 2756 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 56,057 psi | 81% | 3015 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 36,492 psi | 52% | 2789 fps | 95.3% |
| Bofors RP5 | <<locked>> | 80% | 33,953 psi | 49% | 2697 fps | 95% |
| Bofors RP7 | <<locked>> | 80% | 48,428 psi | 70% | 2907 fps | 99.4% |
| Hodgdon H1000 | <<locked>> | 90% | 36,158 psi | 52% | 2743 fps | 95.2% |
| Hodgdon H380 | <<locked>> | 80% | 56,101 psi | 81% | 3041 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 51,706 psi | 74% | 3028 fps | 99.9% |
| Hodgdon H4350 | <<locked>> | 80% | 45,948 psi | 66% | 2894 fps | 98.6% |
| Hodgdon H4831 | <<locked>> | 88% | 41,887 psi | 60% | 2828 fps | 95.6% |
| Hodgdon H4831 SC | <<locked>> | 84% | 40,944 psi | 59% | 2808 fps | 95.3% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 41,336 psi | 59% | 2782 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 58,204 psi | 84% | 3074 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 33,852 psi | 49% | 2772 fps | 95.6% |
| Hodgdon Superformance | <<locked>> | 80% | 47,282 psi | 68% | 2979 fps | 99.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,630 psi | 40% | 1739 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 53,388 psi | 77% | 2969 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 52,852 psi | 76% | 2953 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 51,532 psi | 74% | 2940 fps | 99.8% |
| IMR 4350 | <<locked>> | 80% | 44,034 psi | 63% | 2835 fps | 98.8% |
| IMR 4451 Enduron | <<locked>> | 80% | 49,966 psi | 72% | 2933 fps | 99.7% |
| IMR 4831 | <<locked>> | 80% | 39,450 psi | 57% | 2759 fps | 99.8% |
| IMR 4955 Enduron | <<locked>> | 82% | 40,698 psi | 58% | 2766 fps | 95.4% |
| IMR 7828 SSC | <<locked>> | 84% | 40,059 psi | 58% | 2854 fps | 95.8% |
| IMR 8133 Enduron | <<locked>> | 98% | 36,912 psi | 53% | 2818 fps | 95.2% |
| Lovex S062 | <<locked>> | 80% | 57,058 psi | 82% | 2999 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 47,268 psi | 68% | 2877 fps | 99.9% |
| Lovex S070 | <<locked>> | 80% | 45,658 psi | 66% | 2867 fps | 99.4% |
| Lovex S071 | <<locked>> | 80% | 28,892 psi | 42% | 2493 fps | 95.7% |
| Norma 203B | <<locked>> | 80% | 57,957 psi | 83% | 3058 fps | 100% |
| Norma 204 | <<locked>> | 80% | 44,121 psi | 63% | 2874 fps | 97.9% |
| Norma 217 | <<locked>> | 94% | 32,126 psi | 46% | 2713 fps | 95.6% |
| Norma MRP | 90.4 gr | 80% | 35,549 psi | 51% | 2769 fps | 97.2% |
| Norma URP | <<locked>> | 80% | 44,962 psi | 65% | 2887 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 38,827 psi | 56% | 2838 fps | 95.9% |
| Ramshot Hunter | <<locked>> | 80% | 43,918 psi | 63% | 2884 fps | 99.6% |
| Ramshot Magnum | <<locked>> | 82% | 33,750 psi | 48% | 2684 fps | 96% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,268 psi | 41% | 1781 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 55,782 psi | 80% | 3025 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 54,447 psi | 78% | 3074 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 45,832 psi | 66% | 2920 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 44,193 psi | 63% | 2943 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 30,777 psi | 44% | 2674 fps | 95.3% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 43,352 psi | 62% | 2976 fps | 96.1% |
| Rottweil R 902 | <<locked>> | 80% | 58,610 psi | 84% | 3005 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 52,750 psi | 76% | 2963 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 39,523 psi | 57% | 2749 fps | 95.7% |
| Rottweil R 905 | <<locked>> | 80% | 37,463 psi | 54% | 2749 fps | 96.4% |
| Rottweil R 907 | <<locked>> | 80% | 48,428 psi | 70% | 2907 fps | 99.4% |
| Shooters World Long Rifle | <<locked>> | 80% | 47,268 psi | 68% | 2877 fps | 99.9% |
| Shooters World Precision | <<locked>> | 80% | 57,058 psi | 82% | 2999 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 45,658 psi | 66% | 2867 fps | 99.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 54,447 psi | 78% | 3025 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 52,794 psi | 76% | 2831 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 46,311 psi | 67% | 2822 fps | 99.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 37,144 psi | 53% | 2743 fps | 96.3% |
| Somchem S355 | <<locked>> | 80% | 52,446 psi | 75% | 2956 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 40,263 psi | 58% | 2733 fps | 95.1% |
| Somchem S365 | <<locked>> | 80% | 41,959 psi | 60% | 2838 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 37,985 psi | 55% | 2730 fps | 97.4% |
| Unknown powder | <<locked>> | 80% | 48,138 psi | 69% | 2943 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 58,537 psi | 84% | 2900 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 58,711 psi | 84% | 2963 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 45,078 psi | 65% | 2795 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 48,341 psi | 69% | 2910 fps | 100% |
| Vihtavuori N165 | <<locked>> | 82% | 34,069 psi | 49% | 2625 fps | 95.7% |
| Vihtavuori N540 | <<locked>> | 80% | 58,581 psi | 84% | 2995 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 48,907 psi | 70% | 2959 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 36,492 psi | 52% | 2740 fps | 99.7% |
| Vihtavuori N560 | 92.9 gr | 84% | 39,160 psi | 56% | 2844 fps | 95% |
| Vihtavuori N565 | <<locked>> | 88% | 38,609 psi | 55% | 2812 fps | 95.1% |
| Vihtavuori N568 | <<locked>> | 96% | 44,614 psi | 64% | 2989 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 45,629 psi | 66% | 2838 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 51,706 psi | 74% | 3028 fps | 99.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 28,906 psi | 42% | 2677 fps | 99.9% |
| Winchester Supreme 780 | <<locked>> | 80% | 37,840 psi | 54% | 2723 fps | 96.4% |
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 101 powders for .338 Lapua Mag. Ackley Improved loaded with the .338 | 206gr | Peregrine VRG-2. Alliant Reloder-26 delivers the highest muzzle velocity at 3,261 fps; across all powders the maximum-charge window runs from 1,942 fps to 3,261 fps. ADI AR 2217 gives the best case fill at 100 %, and 101 of the 101 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (480 MPa), the top charges use 53–90 %, leaving at least 10 % headroom. The 206.0 gr projectile in 0.338" calls for a 1:15.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-25 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. Vihtavuori N560, Accurate MAGPRO, Norma MRP rank at the top here: for .338 Lapua Mag. Ackley Improved with the .338 | 206gr | Peregrine VRG-2 they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Alliant Reloder-33, IMR 7977 Enduron, Vihtavuori N170 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.