The technology incorporated into rifles enabled snipers to shoot with accuracy from long distances. Rifles offered an advantage over an opponent armed with a musket or a blunderbuss, both of which were smoothbore weapons. Historian Thomas Sowell writes:
The Pennsylvania Dutch also developed a hunting rifle that was to play a very different role from that intended by these German pacifists. Unlike most European muskets of the time, German weapons had spiral grooves (called rifling) inside the barrel to produce greater accuracy. Some of these rifled muskets were brought to Pennsylvania by German immigrants. Here they developed a new rifle, with a very elongated barrel for even greater accuracy. This product of German craftsmen in Lancaster, Pennsylvania, was originally known as the Pennsylvania rifle. But it acquired fame in the hands of frontier sharpshooters like Daniel Boone and then became known as the "Kentucky Rifle." It later proved very effective in the guerrilla warfare used by Americans against the British during the Revolutionary War.
As the bullet spun, the axis of its spinning was also its flight-path, and the gyroscopic effect keeps the lead ball flying in something very close to a straight line. Projectiles from smoothbore weapons deviate more to the right or left. Historian Geoffrey Norman writes:
The rifled musket was, indeed, a game-changer in the American Revolution, even if it was not quite as decisive as some have made it out to be. American gunsmiths were not the first to cut grooves into the barrel of a musket, thus putting spin to the lead ball it shot. The spin imparted stability to the ball in flight and improved accuracy over the smoothbore by orders of magnitude. German gunsmiths were the first to employ the technique. German immigrants brought it with them to the New World and made the refinements and improvements that became the Pennsylvania (or Kentucky) long rifle and so famously knocked General Simon Fraser out of the saddle at Saratoga and, a few years later, dropped rank after rank of British troops carrying smoothbores that left them outranged and vulnerable to Andrew Jackson’s men at New Orleans. As usual, the British were brave but slow to learn.
The Americans seemed to incorporate rifles into some of their units quicker than the English, and combined with guerrilla tactics, allowed a small number of Americans to effectively harass larger British armies. (The word 'guerrilla' wouldn't be used until later - when Napoleon invaded Spain - but the Americans had effectively conceptualized the technique.) The British army would eventually shirt to large-scale use of the rifle, but only after the United States had won independence.