H&R Topper Jr. Model 490 Greenwing Special DU 20 GA Single Shot Shotgun Markings: The top of the barrel is marked “TOPPER JR. MODEL 490 / -20GA 3’ MOD” with a circle “P”. The left side of the receiver is marked “HARRINGTON & RICHARDSON, INC. / GARDNER, MASS. U.S.A. / U.S. PATENT NO. 3988848