By including the serial number in your question.
You can download one from the Browning website.
SN were not required before 1968
Call Browning
Not sure if this will help. http://www.stevespages.com/pdf/browning_bar.pdf http://www.gunsworld.com/exploded/brngbar.htm
Try on line auctions, want ads, egunparts, ShotGun News.
You will have to call Browning to find out.
Call Browning.
Check the on line gun auction sites, gunstores, newpapers, Shotgun News, Gun List, etc..
Use the link to date this Browning
Matt Eastman's book on Browning.
1965 - (Fjestad's Blue Book of Gun Values)
YOu will have to call Browning to find out. It was made in 1978