A contemporary British officer had this to say about the accuracy of the Brown Bess.
" A common soldier' s musket, if not too ill-bored, might strike the figure of a man at 50 yards, but if fired at a person at 100 yards, one might as well be shooting at the moon, and have an equal chance of hitting it."

However, if you used a patched tight-fitting ball, accuracy would be much improved!!

Brown Bess ammo was issued in a series paper cartridges with balls of decreasing diameter, and so placed in the aammo box, so the soldier could continue firing despite the tremendous buildup of fouling during combat! You can imagine what effect this had on accuracy. Note the Brown Bess has no rear sight! The British fire commands were " MAKE READY" (cock) " PRESENT!!" (point in the general direction of the enemy) " FIRE!!" The Brits did not AIM. at an individual enemy, they just pointed at the enemy front rank!! But the Continental Army did aim at individual enemy soldiers! As well as one can, with no rear sight![X(]

The balls were loaded naked, and held in place by putting the cartridge paper down on top as a wad when rammed. Often no patch was used at all.[] If nothing was holding the ball in place, it could roll away from the powder charge, causing a dangerous situation indeed. Another load used in smoothbore muskets was " buck and ball" , consisting of a full-size ball, and three 00 or 000 size buckshot. Now this load was a real killer at ranges up to 50 yards or so, making it much more likely that SOMWETHING would hit the group of enemy soldiers you were pointing at.

THE BRITISH BAKER RIFLE OF THE NAPOLEONIC WARS