Solution to toy-ish guns: Make camos for each mineral combined with each gun. The camo would be only covering several parts of the gun, and they'd be dark, while still having that professional look that fits the game.
So, what'd you think?
You may need to look closer to see the changes made. If guns can be recoloured like this, there's no need for glows or sparkles or any other childish things, so there's no good excuse for rejecting these, apart from the fact they're just not liked. Also the user can have a choice to switch back to the original colour, so I left parts of the M4 unchanged. I may need to redo these, so feedback would be great. (Including recolouring parts back to their original colour)
(Sorry for the long read!)