I just had this repair work done on a gun. I had used the "tape method", but decided for a variety of reasons to have a "proper fix" done. In an email exchange with my 'smith (Dave Norin) he stated the follow:
The loose barrel fit is caused by TWO worn conditions. 1. The hook/hinge pin wear. 2. Locking bolt wear. The hook/hinge pin of course represent the off face, back and forth looseness. The locking bolt represents the up & down looseness.
The traditional and proper way to correct this is to half-sole the locking bolt, and to dovetail a wedge into the hook and then smoke the barrel breech back onto face...Re-timing ejectors may also have to be done.
Jonty nailed it for the causes.
Pete
