Removing metal on the latch shelf is very critical, a tiny bid makes a very big difference, and it must be done evenly across the whole shelf. First thing I would try is to take a stone and carefully stone off the machine marks on the rear of the barrel, this will make for a more even consistant lockup, most Handi's have fairly course machine work on the rear of the barre. Just opening and closing the action will also wear it in some and make it latch more consistantly. You should be glad it is a little too tight and not too loose. If you can close the action with a piece of paper in the top of the breach then it is not very much too tight. Larry