I have bought a lot of orphaned barrels over the years. Sometimes you get lucky and fitting them takes an hour or two. Sometimes it takes forever and sometimes you just can't get them to work. I had a set of Lefever barrels seven digits off in serial number that just would not go on at all. So it is a crap shoot and Stan is right if the gun is a decent gun just let someone else do it for you because you can screw them up such that they will never fit anything worth a darn.