I think you have to put the use of and the effectiveness of, these firearms, in the context of the military tactics of the colonial period, which were shoulder to shoulder and grouped, in ranks, wide and deep. These weren't sniper weapons. Just 'lobbing' one in,' so to speak, would/could prove effective, much like a medieval bowman that shoots for the range and not a specific target.
I'm not sure if this is fitting here but:
Wilmington, North Carolina
4 -10 July 1781
Colonel Thomas Bludworth wanted to retaliate for a massacre that happened at Rouse’s Tavern in March of 1781. Bludworth’s friend, James Love, had been killed by soldiers of the 82nd Regiment there. Bludworth did not have the force to take on the British troops stationed in Wilmington, but when he was on a fox chase one morning he discovered a tall cypress on Negro Head Point (present-day Point Peter), across the Cape Fear from Wilmington. This cypress was seventy feet to the first limb and the base was seven feet in diameter. The fox was inside the tree and when Colonel Bludworth entered with his dogs he found it hollow. On that day he started planning how to avenge the death of James Love.
The Bludworth’s happened to manufacture sword-blades, pikes, pistols and the best rifles in the area. Colonel Bludworth made a rifle that could carry a two-ounce ball (.83 caliber) from the cypress tree on Negro Head Point to the British formation area on Market Dock in Wilmington. He practiced shooting the long distance at a drawn figure of a man on his barn door. All of these plans he kept secret.
In early July he took his son, Tim, and his servant, Jim Paget, into Negro Head Point on the pretense of hunting fox or raccoon. He told the boys to take along some food for it may be a long hunt. They filled two wallets with provisions and he took an auger, a large jug of water, and “Old Bess” his huge rifle. The trio canoed down the river until they arrived at the tree. The Colonel then told the boys his plan, they would be living in the tree for two weeks or more.
The three of them built a scaffold inside the tree, and , made an opening in the tree with the auger. Other holes were bored in the tree higher up to admit light and air. They also cleared away enough of the leaves and branches so as to have a clear shot at the Market Wharf. The Colonel trusted in the wind, which goes uniformly down the river, to carry away the smoke and the report of the big rifle.
On the morning of the 4th of July the Colonel looked out through the hole and saw a group of British waiting in front of Nelson’s liquor store. Colonel Bludworth took aim and fired, knocking down one of the men. Four other British quickly carried the shot man into the store.
Bludworth fired a second time and knocked a second man down. The trio in the tree could hear the beating of the drums as panic set in.
A column of soldiers marched down to the wharf, and Jim Paget asked if he could try his hand at shooting. The Colonel agreed and Jim took his place in the raised platform. Jim aimed at the formation and fired. The formation broke and ran for cover. Boats rowed across the river looking for the source of the sniper, but none came to the tree. The British thought it was impossible for a rifle shot to be made from there. The snipers called it a day and ate their provisions.
The next morning Colonel Bludworth looked out the hole in the tree and saw no one on the wharf. Jim Paget told the Colonel that around 10:00 the British would line up at the liquor store. At 10:00 the soldiers quickly moved into the store, fearful of the hidden sniper, but when there was no shooting that morning they became more confident and waited in groups around the door of the shops. The Colonel lined up his sights on one of the groups, and fired. Bludworth saw another soldier being dragged into the shop. A dragoon rode up to the dock, peering in the direction of the opposite shore when he too was knocked from his saddle and into the water.
The snipers continued this sport for a week when a Tory told the British that he had seen Colonel Bludworth and two other men go to Negro Head Point with a large rifle of his own manufacture. The Tory told them that he was probably concealed in Negro Head Point and they should cut down all the trees and underbrush that could hide the Rebels.
Colonel Bludworth saw boats coming toward his hiding place and he had Jim close up the hole they had been firing out of. Twenty men landed on the Point and began to cut away the undergrowth with axes. When they arrived at the hiding place of the snipers it was late in the evening. The soldiers decided to cut down that tree in the morning. Ten men were left on the Point, with three sentinels watching over them. At first Bludworth thought of tomahawking the guard by their hidden canoe, but Jim had been discovered by the guard. The sentinel cried “Who goes there?”, but Jim impersonated a wild hog. The guard relaxed, and soon fell asleep. The Colonel took a stick and coming behind the guard he wedged the stick in his mouth, then bound him hand and foot. The three snipers then safely escaped.