When you shoot someone, the AOE damage also applies to the target being shot. That means you are hitting for the guns damage plus a flat 23 at any range. This is obviously ridiculous if it is being stacked on the target you are shooting, because you are hitting the body at close/medium range for 46 and the head for 62. It is also mitigating the damage drop off by being a flat value... which is okay if it is hitting people around him, but not okay if applied to the target.