Enclosed are some photos of a Harpoon Gun?? (as I know nothing else to call it) that I aquired a few years ago. I know absolutely nothing about this or the projectile it fired. It is a centerfire smooth bore with a 1" diameter bore. The gun is all steel weighing 25 lbs. with a 16" barrel and an over all length of 34". The breach is marked “H.W.CHAPMAN PAT’D MAY 15 1877 NEWARK NJ NO. 104”. And before you ask I do have a clearance letter from the BATF to own this short barreled wonder. What I am asking of the audience is what is it and what type of ammunition did it fire? Thanks again for any information you can provide.