To "correctly" install a liner you first drill the barrel with a piloted (pilot is ground to the bore size and guides the bit straight) drill bit. Obviously the bit has to be as long as the barrel and is the same OD as the OD of the liner. Then the liner is silver soldered or epoxied into place. Subtle craftsmans touches would be things like peening the liner at the muzzle end and then refacing/recrowning, rebluing, etceteras.