[DMZFrank]

In addition to the auto sear, the design of the selector lever, hammer,disconnector and bolt carrier differ from the one in the commercial AR-15.

[riverrunner]

Depending on the build date as BATF became more involved the less M16 parts Colt place in their guns.

Colt went so far as to change the trigger pin and receiver pin sizes to satisfy BATF and kiss the government's A$$ trying to maintain their government contracts.

[archy]

In addition to the auto sear, the design of the selector lever, hammer,disconnector and bolt carrier differ from the one in the commercial AR-15. only, without any change to M16/M16A1 parts.

[archy]

In addition to the auto sear, the design of the selector lever, hammer,disconnector and bolt carrier differ from the one in the commercial AR-15.

Yes. But not so with the so-called *Lightning Link* two-piece sear trip, which converts a semiauto AR-15 to Full-auto only, without any change to M16/M16A1 parts.