The title summarizes my problem. I've got an old Berreta Silver Pigeon pump shotgun (1950-1960 ish). It still shoots great, but a buddy invited me to go bird hunting with him next season. Never been, sounds like fun, but when I tried to open the magazine tube to stick a plug in there so I wasn't violating the 3 round max rules, I couldn't get it open. I got the top cap off, and the barrel comes free, but I can't get the next cap off to access the actual spring and tube. There is a hole in the center from where the top cap screws in and holds the barrel in place, and the cap is "knurled"/serrated/etc.? I tried using a strap wrench, and vice grips with leather to protect the metal, but it still won't budge (and did some damage to the metal even though I tried to protect it). Part of the problem is that the cap is only about 1/4" tall, so there isn't much to grab onto without grabing the mag tube below it. Any chance that cap is reverse threaded? Any other ideas on how to get that off, or past experience that works? I really don't want to have to take it to a gun smith just to put the magazine plug in.