Wow, you guys picked up on the correct answer right away. It is a bang stick, late 70’s early 80’s vintage. At that time my circle of friends had a boat and we went diving off the coast of North Carolina about every weekend, weather permitting. There was, and are a lot off WWII era ships sunk by the Germans at the beginning of the war. Ships would hug the cost going southbound in order to avoid the 4 kt Gulf Stream going north. The coast of NC was lit up allowing the German subs to highlight the ships silhouette and plug ‘em with a torpedo. A stat I remember reading from a book called “The Graveyard of the Atlantic” stated that during the first 6 months of WWII the Germans sunk over 60 ships in this area. In some cases people were making it to shore from the light of another burning ship.
Since the ships died a violent death, there were a lot of goodies to be had. Brass portholes, ships binnacle, ships wheel, and in one case a buddy found the rear section of an exploded German torpedo.
All of the ships turned into fish habitats, many with resident sand tiger sharks that could be aggressive at times. Along with my bag of tools, I carried a short multi-use pry bar, one use was as a club. Most of the times a good whack on the snout would deter any shark that got to close and it was mostly the smaller 4-5 footers that were aggressive. Anyway, when that didn’t work, as a last resort, someone would blast them with the bang stick. This would end the dive most of the time depending on blood and number of other sharks.
The bang sticks are designed to be pushed against the target ejecting not only the lead but a huge amount of gas that if hitting the body cavity would fill it up. All I had ever seen was a cartridge holder on the end of a Hawaiian sling or spear gun till I found this one for sale in a dive shop. You wouldn’t see that now. The gun nuts have incrementally taken that right away. This one is in sections with the bungee inside and could be worn on one’s weight belt, freeing up your hands. When needed, take it out and the bungee pulled the sections together. It is made out of stainless steel and aluminum and is smooth bore. A push drives the round into the firing pen. We put fingernail polish around the primer and the projectile of the cartridge to keep water out.
I lost the safety pin that came with it on the first dive. Substituted a clip from a fish stringer that worked better if I had gloves on anyway.
When I got the thing, I wanted to test fire it. I was on dry land and instead of using a melon or the like I used a board. The blast from the explosion filled me full of splinters. If there is an easy way to learn I have a habit of learning the hard way, at least in my youth. It is surprising what age and a little less testosterone does to improve your intelligence.
The shotgun rig in a different post looks like a street sweeper, as it was called. Want to sell it?