I would suggest a way to buff shotguns in a way that makes them a bit more unique. My idea is summed up as: “Shotguns don’t take prisoners”
Basically, the amount of damage which, when dealt by any other gun, would simply down a soldier, would kill the soldier outright when dealt with a shotgun. No down-but-not out, shotguns would just cut out the middleman.
In addition, shotguns should deal the same damage to legs and arms that they do to the lower torso, and shotguns should have dismemberment effects.
The logic of the “cutting the middleman”, at least in my eyes, is that the amount of wounding and damage caused by multiple high velocity pellets hitting all over the body would be too much for a simple medkit to fix, even the magic video game ones. Thus you couldn’t revive yourself and would just die.
This would make shotguns a somewhat lower skill weapon, but they would retain their damage profiles so they only shine up close.