You can tighten the rear by bending the corners up a little on the metal flange that engages the lip on the front of the receiver ring. If it is 2 rivet, be careful when you do it so as not to pop a rivet loose. Easiest way is to use a small brass hammer from the side and bottom, a little at a time. It will surprise you how well it works. I have done it on several carbines through the years.