I got a new stock today and after I put it on, I checked for any wobble. When I shook the stock, the whole receiver extension rotated!:confused: It doesn't rotate very far. I'm guessing the little nub on the receiver plate is keeping it from rotating a lot. I don't understand how this happened. The receiver plate is double staked to the castle nut. This somehow happened recently because I when I got my previous stock months ago I checked for wobble the same way and the RE didn't move.
Possibly a defective lower or RE? Anyone have something similar happen?

