The French Charleville Musket was .69 caliber and the British Brown Bess Musket was .75 caliber. These were the primary military long arms in non-Spanish North America during most of the 18th and early 19th Century part of Colonial Era. Other calibers were popular for Kentucky/Pennsylvania Rifles, but your specimens don't seem bear any evidence of rifling grooves or significant impact deformation. One seems to have a dent of some sort. One wonders if these could have been an ammo spill. These were likely to be the primary arms of the militia members and civilian hunters/settlers. Calibers of these ranged from .25 cal. to .62 cal., with .40 to .48 cal. being most common. All of these above guns are flintlock firearms. If your specimens are truly .50 caliber then they would most likely fall into the latter class of civilian/militia arms. All of this is for naught if these were specimens of pistol ammo, which could also fall into these calibers. Some flintlock pistols were smoothbore and some were rifled, such as dueling arms.