I don't know if Briley still provides this service for pattern welded barrels, but they certainly did back in the early 2000's when installing their chokes in an E.C. Green damascus gun owned by a shooting friend of mine.
The reason for doing so was to correct poorly regulated barrels (cause unknown) that were off by many inches even at 25 yards. My friend bought it as a 'shooter' for the various vintage events that were becoming popular back then and was pretty disappointed to find it virtually unshootable. Briley requested that he provide a goodly number of pattern sheets, from which they eccentrically reamed and threaded both barrels to shoot as they should. I can only say that I witnessed both the before and after results and the gun shot to center thereafter - and saw a lot of use on sporting clays.
What they are doing today, I have no idea.
