You will have to call Colt with the serial number since you did not list it in your question.
your colt combat commander was made in 1972.
Your Colt commander was made in 1976.
That Colt combat commander 70BS69785 was produced in 1978.
1978
1976
Production date 1977.
Production date was 1976.
Production date was 1977.
Colt data at Proofhouse.com
You will have to call Colt to find out.
1978
1978