According to the law of equal and opposite reactions, when a gun is fired, roughly the same amount of energy is imparted on the firearm as is imparted on the bullet. Yet, only a fool would claim that the person firing the gun receives the same amount of "damage" as the person who is hit by the bullet.
"damage" is based on object speed, mass, size, and shape, not just on a "Joule" rating.
no one in the pictures is wearing a mouthguard, and not all are wearing glasses. Since I'm not in the habit of rolling around in the weeds and playing war games, I wouldn't know what the normal rules are.
your clarification is appreciated, but when you throw around terms like "pure ignorance" you might want to carefully check how you are responding.