it doesnt look over powered. Thats how sub machine guns are supposed to be. Deadly at close rang but close to useless at range. If you watch the clip where hes shooting the enemy and has to finish him with a grenade. You can tell that damage is reduced by alot when shooting somebody at range.
It does look a bit over-powered, but keep in mind that he was playing combat training against computers. Plus he never showed himself dying, so it seems like he didn't lose a single gunfight.
The following user thanked Sox for this useful post:
They made it so all SMG aren't good at long range kills. So just throw on an assault rifle and you should have no problem taking down someone carrying an SMG but ONLY if it's not a close ranged gunfight.