Is this a cartridge gun, a muzzle loader or a 12 bore with tight bores? It could be any of them. There were 14 gauge shot guns made but in very small numbers. Parker, Lefever and several European makers made a very few. I recall the King of Spain used a 14. He was notorious cheap and knew if he had only 14 gauge ammo no one could bum a few shells off him. I recall someone who had one saying he took 16 gauge ammo and taper it up to fit snuggly into his 14 chamber. Hulls would split sometimes but they did function. Not a practice I’d try but other are more adventurous than I am.
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