Depends on what side you are, that is, what you want to say. Wether you are expressing amazement or outrage, etc.
So, some ways to express that:
it was a perfect shot
it was a deadly shot
it was a precise shot
it was one shot one kill
it was a fatal shot
I think it could be said about pretty much of any gun, anyway would be a bit unusual to see someone blowing the top of a gun if the gun is a rifle/shotgun (or trebuchet). Blowing the barrel of a small gun (revolver/pistol) is more to the point.
Ah, if you meant the shot, it can be said of any gun.