Note this was written on ipad so spelling mistakes.
Makeshift hanguards, straps, grips, stocks… ylu name it. They would look rugged, mske the weapon heavier than normal military grade.
There could be metal makeshift parts (heavier but gives better recoil control)
Wood would keep the weapon lighter but wear faster and have more recoil.
So you could find a weapon that was stripped for parts and build most of it yourself.
Weight, would like you guess affect stamina, draw and aim time.
Oh this is unrelated but when you stay ontop of a vehicle you should move with it until it reaches a certain speed.
This was more of an idea than a suggestion as I don’t have time to make a fully detailed post, would be great if someone did that.