That’s an AAC Honeybadger made out in Fluttershy-Style.
OK, I’m a bit partial to the goofy-shy Pony, but even if I wasn’t who wouldn’t want such a good gun made up in such flamboyant style?
And since we’re talking flamboyant and Honeybadger, let’s go out with FPS Russia running the gun:
Clearly the folks at Geekosystem weren’t looking hard enough, if they only found three MLP-themed firearms.