I remember the M-16 I had in basic training in 1973 had a Colt trademark stamp on the lower receiver group. I’m not sure of the manufacturers of the M-16 and M-16A1’s I had after that. I believe the M1911’s I carried were all Colt, but now 30 years later, I’m not willing to bet on it.
I think GM manufactured M-16s, under license, because of the Army’s demand, during the VN era. A least, that’s what the Drill Sgt. told us.