You will need to call Colt.
If you call Colt, they will tell you.
It was made in 1966.
made about 1928......................
about 1904
Your colt was made in 1956.
Proofhouse.com has Colt sn data. If not there, call Colt.
Your colt single action army was made in 1906.
about 1883
1919
1903
made about 1877
With that serial Numbe, it was made in 1900.