Ken, I once learned to make the technical mechanics calculations for constructs like that. It's difficult to see the mechanical strength of a design without knowing details and having very much experience in this specialty.


About lightening weapons:

A most extreme example was probably the MG 45, a late-WW2 successor project for the MG 42.
The weight was reduced by much, rate of fire was apparently increased to up to 1,800 rpm (details are not known for sure). I have no idea how they believe soldiers would be able to control this beast on a bipod.


It IS advisable (or at least a debatable option) to reduce weight and durability (not totally the same as reliability) IF you assume that the hardware won't be used much.
Fighter aircraft cannons, weapons for support personnel, infantry weapons in a great war (high attrition) are examples for this.