Sure that is not a 74M? Should have been made in 1974. From the Browning website:
1968-76 In 1969 Browning started using two digits for the date of manufacture which was followed by a four digit code that identified the type of Auto-5:
M=standard weight
G=light weight
This was then followed by the serial number beginning with 1000.
Example: 69G1000 = A 1969 Auto-5 Lightweight 12 ga.. shotgun with a serial number of 1000. M-standard weight
G=light weight
Here is some reading for you- and a link to the owner's manual. Pay attention to the last line about friction rings. Your shotgun was designed by John Browning, made in Belgium by a premier gun maker, and in production for 100 years. It don't get no better than that.
http://en.wikipedia.org/wiki/Browning_Auto-5