Ive just finished watching The Terror, a TV Mini series. It's based on the ill fated Franklin Expedition to find the Passage from the Atlantic to the Pacific via the frozen arctic. It's set in 1845/46 and is a fictional account of what might have happened to them. They were never seen again. The marines on board the 2 ships carry flintlock muskets but also what look like short, hammered shotguns. Are the shotguns percussion? Why could the muskets not be fired that way? The image shows the musket, can't find one of the shotguns used.