This Remington manufactured receiver plug is for the model 550-1 semi-auto rimfire rifle and is in very good condition exhibiting a mixture of original blue finish with a gray patina caused by 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, (WXX) August 1951, (RYY) Nov. 52, (PZZ) June 53, (LB) Feb. 55, (WB) Aug. 55 & (XD) Dec. 1957.