I was given a sears auto loading 12 ga shotgun. Its an autoloader that is the reason it is posted here. What the problem is that it will not cycle a a new round into the chamber. I have flushed what I believe to be he gas ports. They seem to be clear. One thing I noticed was that it is stamped 3" or 2 3/4" magum only. I have been using standard 2 3/4" field rounds. What I was wondering is could that be what it causing the FTF? I do not know much about shotguns so any info would help.