Hello, These might be stupid questions, but I was curious about a couple of things with calibers and ammo types... One is, can a gun use more than one caliber ammunition? Like, in a pinch, could I use .40 ammo in a .45 gun? Are there guns designed to take more than one caliber ammo? Also, is there a limit to the type of ammo a given gun (say a shotgun) can fire so long as the ammo caliber matches? Or are there some bullets that require a specific type of gun to fire? Say I had a flare gun and a shotgun shell that will fit in it. Could I fire the shell?