I'm also talking about the 20th century--slightly more than the first half of it. "Choke" was a required marking on any barrel with more than .008 constriction (and could be stamped on those with as little as .004 constriction, at the maker's request) until the proof laws changed in the mid-1950's. And we are "bothered" about proofs because, thanks to websites like this one and magazines like Double Gun Journal, we Yanks are now sophisticated enough to be able to spot out of proof guns. And while "out of proof" is not always a safety issue, it is nearly always--to anyone knowledgeable buying Brit guns--an economic issue. The price takes a hit if the gun's out of proof.
