This Remington manufactured open sight step marked "R" is for the model 572 Fieldmaster slide action rimfire rifle and is in very good condition with light wear.  (file photo)

Note: Remington model 572 Fieldmaster rimfire rifles with the following serial numbers and / or date codes (month and year of manufacture) have been observed with this part:

Dates: CM (April 1965), RN (November 1966), XU (Dec. 1971) & DX (September 1973 Ser. # 1752987)

Ser. #'s: 1651124 & 1767489