Mike Orlen is one of the best and he's very reasonable with his prices. He's listed in the gunsmith section over on
www.shotgunworld.com . His price list is there also. I had him do a Brng mod. 42 reproduction .410. I shipped the barrel to him and had the barrel completed and returned to me in 6 days! I believe he's getting $55 per barrel for the machine work. Mossburg style tubes are all over the place the same tubes fit Win, Wby, Brng inv. (not Inv. plus) as well as Mossburg and several others.