This needs clarifying - Lancer Systems Beretta 1301 Competition Extension Tube

I ran into the same issue with fit as others here. My 1301 comp is a newer model. The tube as described by others, does not screw down flush to the hand forearm, which causes the barrel not to push all the way into the receiver. The gap is about 1/4 inch. My fix, was to make a spacer by cutting a 1/4 inch slice off of a 3/4 PVC coupling and dropping it onto the mag tube before the extension tube. This allowed the barrel to push tight into the receiver. The manufacturer should machine an aluminum spacer to solve this issue. I plan on replacing the PVC spacer with one I will make from aluminum. Hope this helps.