I only have one critique, and one addition.
Critique:
> you would want to start with disabling locomotion by going for the legs
Aim small, miss small. You want to go for center mass of any target that's trying to harm you. The consequences of missing are...severe.
Which brings me to the addition:
A shotgun with slugs is hard to beat against a robot at close range.
i get the center of mass targeting, the 7.62 in my opinion is too small for that philosophy, if i had free choice of arms i would go large cartridge rather than intermediate such as .375 HK ; 45-70; or yes 12ga aluminum sabot with a thermite core if your into exotic loads
when you hit center of mass you want to do it hard enough that every part of the mass gets damaging energy, the concern would be a distributed network of adaptive intelligent systems hosted in one mobile unit, requireing multiple hits, or overwhelming concusive force.
[im thinking more like black mirror dogs than boston robotics]