Either poorly designed or poorly machined. - DoubleStar M4 Mortar Plate

The clamp hole on the bolt side counter bore was way too deep. Very thin sliver reacting the clamping force. Mounted on an extended carbine buffer and LR308 platform. After firing 10 rounds or so, the mortar plate wobbled on the buffer tube. Tightening the bolt popped it through the clamp breaking out the little sliver of metal the bolt tightened up on. Standard allen wrench not excessive torque just plain junk. I was initally thrilled with the look, even bought a butt pad.......very disappointed. I sent it back for store credit.