I have one Sleever...I'm not sure who did it.1901 ,30' x 2 3/4" steel bbl Greener UL Pig'Gun.I got it from A G & Lang. unfortunately I had to take off the nice leather pad as it was cracked somewhere in around the baseplate, but it had WAY too much Toe sticking out...ouch!....On the underside of the pad was written ."Tony White"..the english maker, I pressume.Don't know if he Re cased the action & sleeved the bbls , or just oversaw the project..or the pad was one of his spares...but the sleeving is a good job, with proper stamp & reproof..I love it.
People say sleeving changes the balance of a Gun, it prolly does, but with the new tubes you have no idea how it felt originaly,unless your having the job done on a gun you already own.. so you just gotta decide if you like the balance as it is now.
Mine now balances with a bit of weight out front, as perhaps a 30" Pigeon Gun should...this is my main target gun, so I put a goodly few sensible PSI 1oz loads through her.....& don't even think about it
franc