5.56x45 ammunition manufacturers during Vietnam war

What companies or government ammo factories were making the M193 cartridge during the Vietnam war for troop use? I’m talking specifically about the cartridge American troops were issued for the m16 rifle. I image Winchester, lake city, and twin cities? Remington? Maybe more?

When I compare Winchester and lake city m193 both of the bullets themselves look different but both are labeled as m193. Who really makes the m193 bullet?

FEDERAL can be added to the list of domestic, Viet Nam era producers of M193

You mention that you have found a difference between Lake City and Winchester labeled M193 “bullets”. Will you please describe these differences, is it profile, weight, jacket material ?

Check the bullet with a magnet. You will find both gilding metal and gilding metal clad steel jacket in M193 from Lake City.