the other day a friend of mine brought up the fact that he was given some powderless 22 shells for some varment control around some out buildings. they are supposedly smaller than a 22short and pack a pretty cool punch, yet, no gunpowder is used! his friend is a gun dealer and travels all over the u.s., and aquires these odditys in his travels. would anyone here have a clue as to what this product is? thanks!