1-9 twist. I purchased a reloading book with specific loads for what i need and am having good results as far as accuracy. Where im having trouble is the case activated powder measure will actually bind up on (imr-4046) and cause excessive pressure on the case. Often ruining the case mouth. I use re-15 for my 308 and don't have this issue but i'm not sure if its because the case itself is stronger. Can anyone reccomend a powder with a lower tensile strength for lack of a better way of putting it. Reloading with a hornady lock n load ap progressive. Thanks, nick.