Argo44, then I would suggest that you find a copy of "Shotgun Technicana" by Michael McIntosh and David Trevallion. There is a very good explanation of the fitting of barrels to the action there, and a whole lot more you'd likely find interesting. It is out of print, and much in demand, so used copies often sell for $100.00 or more. But occasionally you can snag one for less.

Voting for anti-gun Democrats is dumber than giving treats to a dog that shits on a Persian Rug