Proofhouse.com has Colt sn data.
about 1977
around 1965
Produced around 1968.
36 years old
Made in 1978. It is about 31 y.o.
Proofhouse.com has sn data.
About 36 years old, made in 1975.
Blue Book of Gun Values or one of Wilson's books on Colt can help
You must call Colt to find out.
@ 1959
What is the age of a Colt rifle serial SLD25319
made about 1969