How can you find the age or year of manufacture for cooey model 71?

Dependimg on serial# they are all made { or at least offered for sale } between 1966 and 1975 .The later rifles were called mod. 710 buy are essentially the same gun with the same stock.I have 4 of these rifles the earliest ser.# is13 and the latest is 96 .the first gun was bought in1968 and the last was bought in 1973 , so I would guess about 11000 to 13000 were made . hope this helps! A.B.