IMO the design is over saturated, meaning that the colors are too bright and cover up too much of the gun. When this happens, 1) It can hurt the viewers eyes, and 2) The design loses quality and becomes pixelated, which is happening in this picture.
It would look MUCH cleaner if the design was an overlay, not simply "painted on." By that i'm talking about making it semi-transparent, or faded, so the design looks like it is actually part of the gun, not a layer on top of it. One more thing, I would erase some of the design to keep the originality of the gun.
Of course I'm picky because I am a graphics designer, and players might think it's neat, but that's just what I think about the design.
Instead of explaining everything, I did a preview for you.:
There is still a lot more work to be done IMO, but that was a quick edit that makes it looks cleaner.