By model and serial number. Go to proofhouse.com
You will have to call Colt to find out.
Proofhouse.com has Colt sn tables.
about 1892
Proofhouse.com has Colt sn data.
Blue Book of Gun Values
Proofhouse.com has Colt sn tables.
The Colt .45 was issued to the army after trials in 1873 and manufactured by the Colts manufacturing Company.
probably WW1 era.................
Proofhouse.com has Colt sn data.
1919
and the question is: .........................????????
about 1959