The following info can be found here:
http://www.thehighroad.org/showthread.php?t=356710
(I don't know how accurate it is.)
m75rlg
Please note that this list is a general guide and not meant to be exact. There is some dispute regarding the dates on some serial numbers and your gun may actually be a year off from what is listed. The precise shipping date as "lettered" can be several years off depending on model. For the exact date on your gun request the letter from S&W Historian Roy Jinks.
Pre-War N frame.
Year/Beginning Serial
1908
.. 1-------------1926
.. 25000
1909
.. 2050----------1927
.. 28500
1910
.. 5000----------1928
.. 29500
1911
.. 7050----------1929
.. 30000
1912
.. 9100----------1930
.. 34000
1913
.. 11150---------1931
.. 36000
1914
.. 13200---------1932
.. 38375
1915
.. 15250---------1933
.. 41200
1916
.. 15500---------1934
.. 43350
1917
.. 16000---------1935
.. 45500
1918-1919 None--------1936
.. 47200
1920
.. 16200---------1937
.. 48700
1921
.. 16300---------1938
.. 52000
1922
.. 18400---------1939
.. 57200
1923
.. 19600---------1940
.. 59000
1924
.. 20800---------1941
.. 62350
1925
.. 22000---------1942-1945 None
Post-War S Series N frames:
S62,489 S67,999
..1946 - Early 1947
S68,000 S71,999
.Late 1947 Early 1948
S72,000 S72,499
.Late 1948 - Early 1949
S72,500 S74,999
.Late 1949 Early 1950
S75,000 S80,499
.Late 1950 Early 1951
S80,500 S85,999
.Late 1952 Early 1952
S86,000 S94,999
.
Late 1952 Early 1953
S95,000 S102,999
.Late 1953 Early 1954
S103,000 S139,999
Late 1954 Early 1955*
S140,000 S149,999
.Late 1955 Early 1956
S150,000 S175,999
Late 1956 Early 1957
S176,000 S181,999
Late 1957 Early 1958
S182,000 S194,499
Late 1958 Early 1959
S194,500 S206.999
Late 1959 Early 1960
S207,000 S219,999
Late 1960 Early 1961
S220,000 S227,999
Late 1961 Early 1962
S228,000 S231,999
Late 1962 Early 1963
S232,000 S235.999
Late 1963 Early 1964
S236,000 S257,999
Late 1964 Early 1965
S258,000 S261,999
Late 1965 Early 1966
S262,000 S289,999
Late 1966 Early 1967
S290,000 S304,999
Late 1967 Early 1968
S305,000 S329,999
Late 1968 Early 1969
S330,000 S333,454
Late 1969 Early 1970
*Note that a number of N frames with serials in the S138000-S140000 range (and the range may be wider either way) are seen that were shipped much later than the serial would suggest should be the case. In one known example a gun with serial S136431 was not shipped until June of 1958. It's possible that a large block of serial numbers that appear to be from 1954-55 were not actually used until 1957-58. It at least one case a gun has a 5-screw serial and was built as a 4-screw gun.
N Series N Frames:
N1 N60,000
.......1970-72
N60,001 N 190,000
...1972-74
N190,001 N430,000
...1975 77
N430.001 N 550,000
..1978
N550,001 N580,000
.. 1979
N580,001 N790,000
...1980
N790,001 N932,999...
1980-83
Post-War S Series K Frames:
S811,120 S999,999
.1946 48
C Series K Frames: (Fixed Sight Models)
C1 - C233,999
.....1948 52
C236,004 C261,483
.1953
C277,555 C314,031
.
1954 56
C402,924 C405,018
.1957
C405,019 C429,740
..1958 59
C429,741 C474,148
.1960
C474,149 C622,699
.1961 62
C622,700 C810,532
.1963 65
C810,533 C999,999
..1966 67
D Series K Frames: (Fixed Sight Models)
D1 D90,000
.....1968
D90,001 D330,000
..1969 -70
D330,001 D420,000
1971 Early 72
D420,001 D510,000
Late 1972 Early 73
D510,001 D659,901
Late 1973 Early 1974
D659.902 D75000
..Late 1974 Early 1975
D750,001 D870,000
Late 1975 Early 1976
D870,001 D999,999
Late 1976 Early 1977
2D00001 - 2D80,000
.1977
2D80,001 2D99,999
1978
4D00001 6D10,000
.1979
6D10,0001 7D10,000
1980
7D10,001 9D44,500
..1981
9D44,501 17D8,900
1982
17D8,901 21D0883
.1983
K Series K Frames (Adjustable Sight Models)
K101 K614
......1946
K615 K18,731
....1947
K18,732 K73,121
..
1948
K73,122 K84,149
..
1949
K84,150 K104,047
...1950
K104,048 K136,690...1951
K136,691 K175,637...1952
K175,638 K210,095...1953
K210,096 K231,255...1954
K231,256 K266,154...1955
K266,155 K288,988...1956
K288,989 K317,822...1957
K317,823 K350,547...1958
K350,548 K386,804...1959
K386,805 K429,894...1960
K429,895 K468,098...1961
K468,099 K515,478...1962
K515,479 K553,999....1963
K555,000 K605.877....1964
K605,878 K658.986....1965
K658,987 K715,996....1966
K715,997 K779.162....1967
K779,163 K848,781....1968
K848,782 K946,391....1969
K946,382 K999,999....1970
1K1 1K39,500.........1970
2K1 2K22.037.........1970
1K39,501 1K999,999...1971
2K22,038 2K55,996....1971
3K1 3K73,962.........1971
2K55,997 2K99,999....1972
3K31,280 5K6,616.....1972
4K1 4K1,627..........1972
4K1,628 4K54,104.....1973
5K6,617 5K73,962.....1973
4K54,105 4K99,999....1974
5K73,963 6K58,917....1974
7K1 7K26,043.........1974
7K26,044 7K70,577....1975
6K98,918 8K20,763....1975
8K20,764 9K1.........1975
8K20,000 9K100,000...1975
9K1,001 9K99,999.....1976
10K001 24K9,999......1977
25K001 56K9,999......1978 79
57K001 91K6,800......1980
91K6,801 124K000.....1981
125K000 269K9,999....1982
270K000 311K273......1983
1980 Three-Letter Prefix Series Begins at AAA000