AR-15 bolt carrier/upper combo question

[MMcfpd]

Is there any reason that I can't or shouldn't use a regular M-16 bolt carrier in a slick side upper?

 

[Chipperman]

As far as function, no.
Legally, many people feel you are safest to not have any full-auto parts in a semi-auto gun.

 

[MMcfpd]

Thanks, function is my concern.

Considering how many manufacturers, including Colt, now ship ARs with FA carriers I'm not too worried about the legality of using such in an otherwise semiauto rifle.