Thanks for the responses. My wife has taken over my computer due to at home corvid 19 measures. There are very faint markings I cant make out, but no proof marks. They are the only 2 markings on any part of this barrel. It is a 2 screw 5 pin lock with the type 2 hammers. A blast to shoot. Left barrel is 50 thousandths constriction! Right is 30. Shoots 100 percent high.