I have installed several of the 12 ga. Colonial Thin Wall tubes in lined barrels. I have a special piloted reamer made to remove the chrome from the muzzle end for about 3 inches so I could ream and thread for the choke tube.
Not many barrels can be fitted with these thin wall tubes as the bore must be no larger than .728" and the outside no smaller than .820" and concentric as well. Careful measurements have to be taken before I decide to do it or not.
I charge $200 per barrel with 2 tubes supplied plus shipping. $400 for an O/U or SxS.
There is no warranty on blow out or damage from shooting after installation. I do not recommend steel shot to be used with these thinwall tubes.