.
It's not by "serial number".
See if this answers your questions.
Den
REMINGTON SHOTGUN SERIAL NUMBER STRUCTURE
M/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
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”)
M/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
LETTER SUFFIX
SAME STRUCTURE AS THE M/870
M/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
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