I had two Ithaca 37s from the 1950s...I bought 3 different barrels from the Kings Ferry plant in the mid 90s and all of them fit and functioned perfectly with zero gunsmithing/fitting. Just screwed them in and theyre still working reliably. About 15 years ago I gave those Ithacas and the extra barrels to a young cousin of mine in Iowa so could have a shotgun to shoot high school trap with....Shes an adult now and shes using the Ithacas and still shooting deer, ducks, geese, turkeys, varmints, and trap with them with zero reliability issues. Shell probably teach her daughter and son to shoot shotguns with those Ithacas.