I have bought barrels for L.C. Smith's and have found out that I didn't have to do anything but once to have them fit. I have one hammer gun that has 4 other barrels plus the one it came with and the only barrel I had to work on was a Field Grade with Armor steel barrels. This one I had to take some of the chamber faces as it would not let the entension rib go fully into the slot in the receiver. I also took some off the hook because I didn't want to take much off the chamber side. The others all fit like they originally belonged to the gun. This hammer gun is from 1908 and I bought it when hammer guns were not popular for $75.00, the barrels were cut to 25 3/16". The barrels range from 1899 to 1927 and the 1927 set is from a Specialty grade with 32" barrels, ejectors and a ventilated rib. The hardest thing is fitting a forend on because you cannot modify the forend to the original set of barrels, so on the other barrels all the work is done on the barrels.
Since all L.C. Smith's were production guns all the barrels were set on a jig to get the loop and the lug to be in the same place on all guns. Higher graded guns went to various skilled workers for wood choices, checkering, engraving, etc.
Also to defend L.C. Smith's because many critisize about the cracks behind the locks, this is from using American walnut which is not good for side lock shotguns. I have never seen a Syracuse L.C. Smith with cracks behind the locks, this is because they used European walnut.
