Call or email Remington and give them the serial number, they will tell you when it was born, however keep in mind they do make errors.

Back up what they tell you with this information;
DECODING REMINGTON SERIAL NUMBERS
Model 870 LETTER PREFIX
1950 TO APPROX 1968: NO SERIAL NUMBER PREFIX
1968 TO PRESENT: LETTERS USED (IN SEQUENCE)
S-68, T-74, V-78, W-84, X-90, A-91, B-94, C-97, D-01, AB-05

Model 870 LETTER SUFFIX (DESIGNATES GAUGE)
V 12 GA. (2 3/4”)
M 12 GA. MAGNUM (3”)
A 12 GA. “SUPER” MAGNUM (3 ½”)
W 16 GA. ( 2 ¾” )
X 20 GA. “HEAVY FRAME” (DISCONTINUED)
N 20 GA. “HEAVY FRAME MAGNUM” (DISCONTINUED)
K 20 GA. “LIGHT WEIGHT” (“LW”) (ALSO INCLUDES M/1100 “LT”)
U 20 GA. LW MAGNUM (ALSO INCLUDES M/1100 “LT”)
J 28 GA.
H .410 BORE (2 ½” OR 3”)

Model 1100 LETTER PREFIX
1963 TO APPROX. 1968: NO SERIAL NUMBER PREFIX
1968 TO PRESENT: LETTERS USED (IN SEQUENCE)
L-68, M-74, N-78, P-85, R-90

Model 1100 LETTER SUFFIX
SAME STRUCTURE AS THE Model 870 listed above

Model 1187 LETTER PREFIX
1987 TO PRESENT: “PC” 12 GA., 1999 “TL“ 20 GA.,
2000 “SM” SUPER MAG.

LETTER SUFFIX
NO LETTER SUFFIX ON THIS MODEL

Then look on the left side of the barrel near the receiver and look for a two letter date code stamp and follow this chart with the first letter being the month and the second being the year the barrel was made;



Month
B - Jan L - Feb A - Mar C - Apr K - May P - Jun
O - Jul W - Aug D - Sep E - Oct R - Nov X - Dec

Year
M - 1921 N - 1922 P - 1923 R - 1924 S - 1925
T - 1926 U - 1927 W - 1928 X - 1929 Y - 1930
Z - 1931 A - 1932 B - 1933 C - 1934 D - 1935
E - 1936 F - 1937 G - 1938 H - 1939 J - 1940
K - 1941 L - 1942 MM - 1943 NN - 1944 PP - 1945
RR - 1946 SS - 1947 TT - 1948 UU - 1949 WW - 1950
XX - 1951 YY - 1952 ZZ - 1953 A - 1954 B - 1955
C - 1956 D - 1957 E - 1958 F - 1959 G - 1960
H - 1961 J - 1962 K - 1963 L - 1964 M - 1965
N - 1966 P - 1967 R - 1968 S - 1969 T - 1970
U - 1971 W - 1972 X - 1973 Y - 1974 Z - 1975
I - 1976 O - 1977 Q - 1978 V - 1979 A - 1980
B - 1981 C - 1982 D - 1983 E - 1984 F - 1985
G - 1986 H - 1987 I - 1988 J - 1989 K - 1990
L - 1991 M - 1992 N - 1993 O - 1994 P - 1995
Q - 1996 R - 1997 S - 1998 T - 1999 (*) U - 2000 (*)
V - 2001 (*) W - 2002 X - 2003 Y - 2004 Z - 2005
A - 2006 B - 2007 C - 2008 D - 2009 E - 2010
F - 2011 G - 2012 H - 2013 I - 2014

Merry Christmas Everybody

Please keep in mind that often times barrels have been swapped on many guns so the stars may not line up between what Remington tells you, the serial number decode tells you, and the barrel decode tells you!
And some barrels do not have the date code on them at all.

All 1999, 2000, & 2001 models did not have a barrel code on the left side of the barrel..... Instead Remington put it on the end flap of the box it came in.

Good Info...Thanks for posting !!