A harmonica gun or slide gun is a form of firearm which was breech loaded with a steel slide, containing a number of chambers bored in it and which were filled with projectiles. Most harmonica guns are percussion cap guns, although some designs exist for compressed air guns. In percussion cap guns, each chamber contains a separate primer, powder charge, and projectile. The slide was inserted in an opening in the breech action and could be advanced by releasing the camlock, moving the slide by hand. The gun comes in both pistol and rifle models, as well as single-action and double-action.
The most famous maker of harmonica guns was Jonathan Browning, father of John Moses Browning. Commencing in 1834 in Quincy, Illinois, he began to make harmonica guns and more conventional revolving rifles. He continued to improve on the principle after he became a member of The Church of Jesus Christ of Latter-day Saints and emigration to Nauvoo, Illinois, and finally Ogden, Utah.
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