The gun was the heaviest load to carry so the gunner was picked by size. It was normally carried balanced on a shoulder while hanging onto one of the bi-pod legs. Most gunners found some way of padding it so it wouldn't hurt their shoulder. Some guys wired a C-ration can on the side to act as a guide for the ingoing ammo.
The M60 was referred to as a gun. All the other light infantry arms were referred to as weapons. I learned a short little poem about that in basic training when I mistakenly called my M14 a gun....
You figure it out.