This Remington manufactured open (rear) sight screw is for the model 550-1 semi-auto rimfire rifle and is in very good condition with light wear.  (file photo)

Note: Model 550-1 rimfire rifles with the following date codes and years of manufacture have been observed with this part: (DUU) Sept 49, (EUU) Oct. 49, (CWW) Apr. 50, (EWW) October 1950, (LXX) February 1951, (WXX) August 1951, (LYY) February 1952, (RYY) Nov. 52, (PZZ) June 53, (LB) Feb. 55 & (WB) Aug. 55.