For the Colt positive special ,it was in 1934.
The Colt police positive .38 with sn 8707 was produced in 1906.The second year of production.
For the Colt police positive .38 revolver, proofhouse,com shows 1907 as the production year.
Size
You can find out at Proofhouse.com in the Colt tables.
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Good revolver.
Proofhouse.com has Colt sn data.
Check the butt
A type of DA revolver made by Colt.
made about 1972
Look on the butt of the revolver