I had the opportunity to watch Larry Potterfield’s video again this evening. More details:
The loose breech-barrel gap, before repair, measured .006”.
He used green Loctite, not epoxy, to hold the stainless shim in place, and carefully trimmed the overhanging shim stock even with the sides of the barrel lug.
The initial result was that the action wouldn’t quite close. This was remedied by sooting the rear of the barrel to disclose the high spots when breech closure was attempted. Those shiny high spots were lightly filed. Re-sooting and re-filing were repeated until the breech could first easily close, exhibiting even barrel-breech contact all the way ‘round, with no gap whatsoever - just like a Holland & Holland.
