This is the Brown Bess musket, the main weapon of the British Army during the American Revolution. The Patriots also used this musket until they could get hold of the French version, the Charleville muskets. Muskets cannot fire a ball in a straight line, soldiers often did not even look at what they were shooting at (to protect their eyes from the flash). Success depended on the mass of firing, not the accuracy. In any event, it was cannon fire that killed most men in battle in those days.