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37 years old. A Colt police positive special with that serial number was made in 1972.
That model was produced in 1922.
1929
Colt official police with serial # 904734 was produced around 1965
Made about 1972, 37 years old, for a Colt police positive special with that serial number
police positive special made about 1920
1919-1922
1967
1907-1909
Around 1943.