Unfortunately mach1, i live in a small town in northern british columbia, cant recall ever having seen a BR shooter at our range! But, thanks to the magical interweb....all the knowledge of the world is at my fingertips thanks to folks like you!
I figured this out on my stock PSS that shoots amazing. I went through and checked all my screws, checked all my ammo, and was almost ready to pull the scope and install a "proven" scope. And then I noticed a shiney spot on my sling stud lol. Adjusted my bags to miss the studs during recoil. "Oh well heck!" lol.I saw it mentioned earlier. Make sure your sling swivel studs aren't making contact with the bag on recoil. Been there, done that.
This ^^^^.You will need to play with the position of the bags, with thin stocks I bring the front bag bag towards the action.