Lazy stroking?
Any dimples in the mag tube?
Spring and follower and check the shell latches, I always upgrade with S&J’s delrin follower and their mag spring. You’ll have to trim the spring to size as it comes long, one spring will do a factory reg length mag spring and an longer spring for the +2 factory extension.
Look at the shell latches on the inside of the receiver. They're staked in place one on the left and the other on the right. These latches control the release and retention of the shells from the tube magazine as the bolt travels back. If there is a problem with either one of these latches, they can cause your gun to not release shells or release more than one shell.



























