You didn't mention if this was documented from records or from observation, but there are cases where documentation doesn't help. During WWII the Flannery Bolt company made replacement barrels for the 1911/1911A1 pistols. It is documented from records that Ithaca used some Flannery barrels in regular production when High Standard barrels weren't available. Today is is common to find Flannery barrels in Ithaca pistols, but since Flannery produced replacement barrels, they too are also common. Now 65 years later it is impossible to tell if the Flannery barrel is original to the pistol or was replaced before the pistols became collectible. A High Standard barrel in an Ithaca is not questioned, but a Flannery barrel always leaves the question as to whether it is original or not.