The Itajubá Model 954 Mosquetão is an example of a Rifle
A rifle is a firearm with a stock and a barrel that has a spiral groove or grooves ("rifling") cut into its interior. The rifling produces "lands," areas that make contact with the projectile (usually a bullet), imparting spin around an axis corresponding to the orientation of the weapon. When the projectile leaves the barrel, the conservation of angular momentum improves its accuracy and range, in the same way that a properly thrown American football or rugby ball behaves. The word "rifle" originally referred to the grooving, and a rifle was called a "rifled gun."
Typically, a bullet is propelled by the contained deflagration of an explosive compound (originally black powder, later cordite, and now nitrocellulose), although other means such as compressed air are used in air rifles, which are popular for vermin control, hunting small game, and casual shooting ("plinking").
Overview
Originally, rifles were sharpshooter weapons, while the regular infantry made use of the greater firepower of massed muskets, which fired round musket balls of calibers up to 0.75 inch (19 mm). Benjamin Robins, an English mathematician, realized that an extruded bullet would retain the mass and kinetic force of a musket ball, but would slice through the air with much greater ease. The innovative work of Robins and others would take until the end of the 18th century to gain acceptance.
By the mid-19th century, however, manufacturing had advanced sufficiently that the musket was replaced by a range of rifles—generally single-shot,breech-loading—designed for aimed, discretionary fire by individual soldiers. Then as now, rifles had a stock, either fixed or folding, to be braced against the shoulder when firing. Until the early 20th century rifles tended to be very long—an 1890 Martini-Henry was almost six feet (1.8 m) in length with a fixed bayonet. The demand for more compact weapons for cavalrymen led to the carbine, or shortened rifle.
History
Origins
Muskets were smooth-bore, large caliber weapons using ball-shaped ammunition fired at relatively low velocity. Due to the high cost and great difficulty of precision manufacturing, and the need to load readily from the muzzle, the musket ball was a loose fit in the barrel. Consequently on firing the ball bounced off the sides of the barrel when fired and the final direction on leaving the muzzle was unpredictable. (In the late 1800s, the term "rifled musket" was used to distinguish between smoothbore and rifled long arms.)
Early warfare was conducted in a way that did not require great accuracy, so the performance of muskets was sufficient so long as a hit amongst a block of men could be made.
The origins of rifling are difficult to trace, but some of the earliest practical experiments seem to have occurred in Europe during the fifteenth century. Archers had long realized that a twist added to the tail feathers of their arrows gave them greater accuracy. Early muskets produced large quantities of smoke and soot, which had to be cleaned from the action and bore of the musket frequently; either the action of repeated bore scrubbing, or a deliberate attempt to create 'soot grooves' might also have led to a perceived increase in accuracy, although no-one knows for sure. True rifling dates from the mid-15th century, although the precision required for its effective manufacture kept it out of the hands of infantrymen for another three and a half centuries, when it largely replaced the unrifled musket as the primary infantry weapon.