Damage Model is all over the place

I have noticed major inconsistentcies in the damage model for some weapons and most vehicles. 

Rocket damage from helicopters, 50 cal damage from mounted guns, and machine gun fire damage are all way too low. It doesn't make any sense that you have to hit someone six times from a 50 cal mounted gun, but they can kill you in a couple of 556 shots. Same thing for the tanks and anti-tank ammunition when shooting at infantry. Those should cause more damage across a wider radius. 

Also, the semi automatic DMRs are underpowered too. 

On the other hand, I feel like the shotguns and SMGs are overpowered.