Proofhouse.com has Colt sn data.
1968. That year began with SN 2030404. 1969 began with SN 2172336.
year 1959
1947
The year that the Savage model 99 250-300 with a SN of 337166 was made was 1941.
Your Glenfield was made in the year 1974.
You will have to call S&W with the sn to find out.
No published sn data.
http://armscollectors.com/sn/windates.htm The year of manufacture for serial number 3937694 is 1974.
Made from 1932 -1955. 5,100 made. Sn range @ 1000-6,100
Made in 1934.
it was made in 1954