Thread: Double grouping

You describe classic double grouping as caused by crap bedding when the action jumps between two rest points due to recoil. Other things that influence barrel harmonics like changing hold, touching the barrel or preloading on a bipod so a free floated barrel has a contact point occasionally can also cause it.
I thought i had it once but it turned out i had a mixed box of 147 and 165 grain projectiles all at same coal, my how I laughed.