I have heard that some AR-15 manufacturers have their manufacturing operations done outside the US because it is cheaper in terms of labor and regulations (foreign country's). Does anyone know if this is true? Specifically, what part of the AR-15 is manufactured outside the US? Does it conform to any MilSpec standards?
I know for sure that some 1911 ACP parts manufacturers have outside operations to make some of the 1911 parts but I am not so sure about the AR-15. Any info on this?

Umm, pretty much none of the big name guys.

CMT,RRA, Stag, Colt, Bushmaster, Armalite, DPMS, DSA, Les Baer, LMT, BCM(coming soon), Sabre Defence, Ameetec, Mega, Superior Arms, etc..

All made in the USA

WIZZO

With Colt's purchase of Diemaco, technically I guess you could say Colt.

Dlask in BC manufactures AR's

www.dlask.com/

Germany
Phillipines
China

I do not think the government lets you import the major portions of non sporting firearms anymore. They put a halt on most of the kits coming in.
www.atf.treas.gov/firearms/081205openletter.pdf

Colt's has used some Canadian Diemaco parts for a number of years.