Quote Originally Posted by Storm Bringer View Post
as Haighus mentioned, they needed the length, plus the shorter barrelled carbine type guns were even less accurate than the "shotgun with only one ball" spread of a regular musket.

also, the standard formation was only 3 ranks deep anyway, precisely to maximise the amount of shooters. 90% of the time, if you see a reference in a battle to a "column" of men that is 10-12 ranks deep and 30-40 men wide, normally, it is a column formed by three or four 3 deep lines "stacked" close to one another, which was supposed to deploy into a line before contact and thus bring every musket to bear.
Indeed, 3 ranks was the standard "line" for most armies of the 18th and 19th century. The British were an exception in using only 2 ranks, and they also trained with live ammunition (which many other nations considered a waste of bullets), so usually had a higher rate of fire. The third rank was basically a reserve to fill out losses and thicken the line against cavalry surprise, they couldn't fire.