Mike,
The Germans sold 24 gage cases (to be loaded with bullets) in various lengths. It may not have been a nominal 577 Boxer, but you obviously have cases and bullets so since you can't buy ammo at the Western Auto it doesn't matter. Shooting these old guns is a "trip", isn't it. I don't know if anyone told you, but the crown V on the rib is a Vorrat Zeichnen, which means it was already completed and for sale when the 1891 proof law became effective March of 1893 and lack of proof marks was not a violation.
Mike
