“Doesn’t the M-60 come with a quick change barrel?”
Yes it does.
While I believe you could build a lighter suppressed barrel system for the 60 it would still have the same problem with heat build up.
You cannot escape the laws of thermodynamics.
The Maxim solved the problem by being water cooled.
I believe it weighed substantially more. There is a reason most military establishment now use general purpose machine guns.