>>8>implying his arm was not his gun.
If you keep track, Vash actually has three guns in the series - His pistol, a machine gun hidden in his arm, and his "fuck you, moon" gun that
is his arm. He's the Trigun.
Presumably his brother knives has the same set up, since they've both got a pistol and "fuck you, moon" gun-arm. I forget if Knives pulled a machine gun out of his arm at some point or not.