1 millimeters = 0.03937 inches See http://www.chapelsteel.com/millimeters-inches.html 17.0 = .670" 16.3 = .642" 18.7 = .736" 18.4 (usual c. 1900 Belgian 12b) = .724" 18.0 = .709" Choke markings may be found after 1924. 1 kilogram = 2.20462262 pounds 1.3555 Kg = 3 pounds May also be stamped '1K3555' May be found after 1924 but without the decimel.