Charlie,
You need to look for a very little circle, or oval stamped on either the barrel, or receiver, usually on the barrel, near the receiver, sometimes on the outside of the receiver, but never on the inside of the receiver. It is very small, sometimes you need a magnafying glass to make out the number(s) and letter. The letter is the date code key, if you can find the letter, match it to this, and you have the date of manufacture.
Stevens / Savage 24 date codes.
--------------------------------------------------------------------------------
A 1949 B 1950 C 1951
D 1952 E 1953 F 1954
G 1955 H 1956 I 1957
J 1958 K 1959 L 1960
M 1961 N 1962 P 1963
R 1964 S 1965 T 1966
U 1967 V 1968 W 1969
X1970
"Collectors will find a date code stamped on every double-barrel shotgun in the Stevens brands produced between March 1949 and December 1968. Usually, it is behind the hinge pin or ahead of the trigger guard on the bottom of the frame. It will appear as a small circle containing a number and a letter. The letters correspond to the years shown in the following table. Significance of the numbers is not known."*
*From page 1101 of Ned Schwing's 2004 Standard Catalog of Firearms, 14th Edition, published by Krause Publications of Iola, WI.
I would like to add that I have found this circle, or oval, containing one or two numbers plus a single letter, just about anywhere and everywhere on the frame, but only on the outside of the frame, never inside. I have also found the circle or oval with letters and numbers on the barrel clusters, on the shot barrel or on the barrel assembly lug block. While the letter within the circle always match on factory matching barrel and frame, the numbers never match, or at least that has always been my experience. These Date Codes are also present on the Model 94 frames and barrels, andI am sure on many others.
The marks on the inside of the frame, where the lower barrel seats when closed, are what I would call assembly stampings, and match frame to barrel, found on underside of shot barrel near forend lug, and also sometimes found on the butt stock under the butt plate.
