This Mossberg manufactured receiver & barrel assembly is for the model 51M(a) semi-auto rimfire rifle and is in very good condition exhibiting a brownish gray patina with some original blue finish and light wear. The receiver is the only part on the model 51M(a) rifle that is tracked as a firearm therefore it will need to be transfered through a dealer. Receivers do not qualify as a C&R based upon BATFE's guidelines. (file photos)