Hi, I recently bought a Benelli M4. After successfully putting 400 rounds through the shotgun, I have began to develop problems. After firing 1-2 rounds, the magazine cap becomes loose and the barrel will literally jump loose out of the shotgun. Obviously, I have tightened down this camp as tight as humanly possible. Does anyone have any advice on fixing this issue? Is using loctite an option or do I have other issues that are causing this problem? Thanks, Phil