Are you sticking the front of the forearm into the barrel ring first, then bringing the back of the forearm to the barrrel? When I assemble mine I never have a click. If the receiver and barrel go together fine I wouldn't worry about it. I had a question for benelli customer service, but they won't reply or get back to me. As for the serial number I have no idea. If it ends up being a problem I would just confront bass pro shops.