Now that I know what to look for, I've uncovered a half dozen of these Captured and Collected aka C&R arms in my collection - and as you say, two are in crisp, almost new condition. One if a Model 1842, Springfield 1853 dated lock, Harpers Ferry Barrel (date not clear), and it has two "Q" stamps, almost on top of each other, with the stamp rotated a quarter turn between the two strikes. The other is a Barnett Model1853 with a confederate view circle cartouche on the top of the comb just ahead of the butt plate tang, and an "8" stamped ahead of the guard. This 8 is the same size and location as the more common letter stamps.