Looks great, however I was wondering if you could make it a little bit more dense/visible? It's nearly impossible to see except against a dark background.
If possible, I would also recommend making it more "explosive" rather than having the smoke creep out of the barrel, per se. And (I feel like an ass for being so picky right now :p) is it possible to make the muzzle flash more transparent so that it's not so bright in daylight?