Much to my surprise I might even be able to contribute to this thread.

I have a Rigby 16 g that was re-sleeved (fluid steel to fluid steel) and re-proofed in 1955 for a 2 1/2" shell at 3 tons PSI. The join is barely visible and this is with the bluing at about 60%


I have become addicted to English hammered shotguns to the detriment of my wallet.