Rifleman

A rifleman is an infantry soldier armed with a long, rifled firearm. Although the rifleman role had its origin with 16th century hand cannoneers and 17th century musketeers, the term originated in the 18th century with the introduction of the rifled musket. By the mid-19th century, entire regiments of riflemen were formed and became the mainstay of all standard infantry. Rifleman became a term for any common infantryman.

Units of musketeers were originally developed to support units of pikemen. As firearms became more effective, the composition of these pike-and-musket units changed, with pikemen eventually supporting the musketeers particularly against cavalry. The last pike regiments were dissolved by the 1720s, as pikes were superseded by the invention of the bayonet. This converted the musket into a pike for those situations where it might still be useful, such as following up volleys with a charge, crowd control, or defensive formations.

Smooth-bore weapons, such as the musket, had always been recognised as inaccurate and required massed volleys to be effective. Aimed fire, with targets individually chosen and fired upon at the initiative of the individual soldier, was not possible until the development of rifling in the barrel. This imparted spin to the bullet, greatly improving its ballistic performance and giving greater range and accuracy, as opposed to a smoothbore where the ball actually 'bounced' down the barrel. However although this impeded the accuracy of a smoothbore it was an advantage when loading from the muzzel, as the musket ball slid down the barrel quickly and easily with the ramrod being used mainly to compress the powder charge at the base of the barrel. Rifles instead required the ball to be rammed all the way down the barrel, a slower and more laborious procedure. This meant that the soldiers chosen for this role needed to be good shots, resilient, brave, and resourceful. Riflemen were trained to act in isolation and were dispersed in teams of two, defending each other while they re-loaded. They were still vulnerable, especially to cavalry, as they could not present the solid wall of bayonets a larger mass of soldiers could. These factors: the time and expense required in training, the limited number of suitable recruits, and the specialised roles and situations where they were most effective meant they were highly prized, given special privileges, and used sparingly rather than squandered.

...
Wikipedia