Certainly wouldn't argue with any of you more astute gentlemen about David's Regulation Terrier, or whatever you jokingly call it.

Roy's letter, to me, is the clue as to how the factory looked at it when he said the factory supplied whatever someone ordered. A "Regulation" is no square-butt gun, in the true sense of the word. It is just a round-butt gun cut for the rebated, square-butt shape stocks.

My high school composition teacher used to call this sort of thing "picking of nits" and always implored us to "just say what you mean!" It may be the stock and trade of a true collector, but I think this is what S&W did. Someone made up a bunch of 4-inch guns with the plain round-butt frames and they sold them. That's all.

(Great discussion and pics - thanks.)