There was a video of a guy on one of the black powder forums that came across several old hollow aluminum arrows from the 1970's. Apparently he discovered that he could fill them with black powder and wedge a 209 primer in the business end of the arrow. He shot one against a concrete wall and boom.
Back in the 1950's and 1960's, many Florida fishing boats carried a spear that held a live shot gun shell in the point. If they had trouble with a large shark on the line and along side the boat, they would stick the shark on the head and blow it's brains out with the shotgun blast.
As I said above, old tech.