Shooting a full propane cylinder with a firearm will cause a Hole in cylinder and allow propane to spew out. But it will NOT cause it to explode or a big flash etc.
Must have a source of 'ignition' to light off the propane VAPOR
MythBusters episode 95. Look it u
Why I stated full metal jacket not a lead bullet. A FMJ will cause ignition when it strikes the metal of the cylinder. I've tried it before. Makes a helluva bang. Actually, a 223 light armor piercing round works best because the pill has a steel insert inside.