Moseberg 750

While it might not fire as fast as semi-automatic shotguns, this packs enough stooping power to go through most body armor in one shot.

Overview
This pump action shotgun can hold a number of different types of ammunition, but it typically fires super charged pellets encased in plasma. This means the plasma burns through shielding while the pellets punch through the body armor. It only holds six shells so if the users is facing a lot of enemies, they will have to reload quite a bit. However, it has amazing range for a shotgun. It is favored for those who need a battle tested system in an urban conflict or a close quarters battle.