AR15.com has a good listing.
You will have to call COLT
Colt data at Proofhouse.com
No such sn in the AR-15 series
You need to call Colt
you will have to call Colt to find out.
You will have to call Colt
Proofhouse.com has Colt sn data.
1974
1971
About 1976
1986
1970