customizeing barrels

I am a machinest that customizes barrel for single shot rifles in the powder burning world however i know nothing about pellet rifle barrels plan on learning .does anyone know if bore and groove sizes are .177 and .222.like to know how hard it would be to rebarrel various makes of air rifles.if anyone has ideas were i might find a book or a web sight that to learn on this subject it would be a big help.any ideas on which barrel makers do pellet rifle barrels. if there is a diffrence