Another fix is to bush the firing pin hole . The old time real gunsmiths did this on a regular basis to repair the old single shot rifles to repair the same problem. Check out Frank Dehaus's book (Spelling of last name?)they made a bushing with a small flange, cut the firing pin hole out , pressed the bushing in and no more slack in the pin!Many old rifles were repaired this way and improved accuracy by more constant strikes on the primer.