I went to Parris Island USMC bootcamp in 1981, so it's been awhile. Until I watched the story posted I was 100% sure I saw "Mattel" somewhere on the M16 that was assigned to me. I would have bet BIG money on it. I'm not sure about that now. Maybe one of the DIs put that memory in my head???
Mattel was always a myth to me but the real fact was GM's Hydra Matic division built the most accurate and reliable M16A1 of the 3 you could draw from an arms room rack
Now, as for the one about Harley-Davidson building components for Bell Helicopters, that is actually true.
H&R also built M16A1 rifles. That went unmentioned in the article...as was Colt and Armalite who designed the original AR-15 the M16 sprung from and from whom Colt bought the design and rights to.