First Issue, 1950-1973. Second Issue, 1973-1981.
That Colt cobra was made in 1976.
Proofhouse.com has Colt sn data.
Colt data at Proofhouse.com
check at: proofhouse.com/colt/index.html
1970
1965
1965
Proofhouse.com has Colt sn data.
That sn doesn't fall in the Cobra range.
1967
1956
Proofhouse.com has Colt serial numbers you can look up.