Most likely to distinguish non-lethal from Lethal, if you ask me the color looks better than the normal ones. Don’t trust me on that one but that’s most likely the reason why just so officers don’t accidentally apply lethal instead of non-lethal also makes it easier to distinguish the lethal shotgun from the non-lethal one.
I’ve recently wondered upon the forums, I like probably most of you play LSPDFR. I am a photojournalist for an independent media company that I own, so I might place photos I take every once in a while once I find the appropriate forum for that.