What continues to surprise me is the number of dealers who specialize in vintage guns but can't measure wall thickness. Bravo to those who provide those measurements on their websites!
Vintage Doubles (Kirby Hoyt) and Champlin Arms are two that do. I also wish, assuming they don't give you all the pertinent data in their description, that they'd all include good, legible photos of the barrel flats and water table. Those answer a lot of questions about proof status, when the gun was made, etc. I know Tom Bryant at Cabela's has worked with his Gun Library managers to post photos of the barrel flats and water table on British and vintage European guns, although most of them can't measure wall thickness.
Lloyd, one difference between American and foreign guns when it comes to inspection is knowing how to read proofs. American guns provide very little in the way of proof data. Chamber length wasn't marked on most American doubles until 2 3/4" became pretty much the standard. (Always best to measure, but best to assume that an American double isn't 2 3/4" unless it's so marked, or if it measures 2 3/4" but isn't so marked, it may have left the factory with short chambers. (Some folks here can tell you--via catalog copy, factory records etc--when American makers switched to the 2 3/4" standard. But it's a slippery slope, because they didn't all do it at the same time, and a given maker didn't switch all gauges to 2 3/4" at the same time. Complicated!) It's also worth it to invest in a bore and choke gauge, which on many foreign guns will tell you whether the bores have been honed from their original diameter, and will also give an accurate reading of choke constriction--which isn't marked on most European guns, nor on many vintage American doubles (Ithaca and Winchester being exceptions).
