Rac-Em-Bac Bow Mag
This odd piece of plastic is actually an explosive arrowhead that uses either the .38 Special or .357 Magnum cartridge. Upon impact with a target, the cartridge is pressed up against a firing pin that causes the detonation. Since there is no chamber to support the ammo, the case ruptures inside of the target causing massive internal trauma.
However it seems that there are reliability issues with these things. Some users report not being able to get the round to go off. It needs a sufficiently hard target to compress the cartridge against the firing pin. There is also the legal issues and hunting laws that have to be taken into consideration. They cannot be reused since the explosion rips the plastic shell apart. MSRP is about $40 for a package of 6. (GRH)