Spiral grooves turned a wobbly musket ball into an accurate rifle shot
A musket ball sat loosely in its smooth barrel, rattling against the sides and leaving the muzzle in an unpredictable direction. Cutting spiral grooves inside the barrel made the projectile spin, and that spin kept it stable in flight, much as archers had long twisted their arrow feathers for accuracy.
The raised ridges between a rifle's grooves, called lands, grip the bullet and twist it as it travels down the bore. Once it leaves the muzzle, conservation of angular momentum keeps the spin going, giving gyroscopic stability that improves accuracy and effective range. Originally the weapon was called a rifled gun, from an old verb for cutting grooves with tools.
European grooved barrels were reportedly being made by 1440, and Gaspard Kollner of Vienna developed them further around 1498, though some scholars credit a joint effort with Augustus Kotter of Nuremberg around 1520. In the early 18th century the English mathematician Benjamin Robins realised an elongated bullet would carry the same momentum as a ball but cut through the air more easily. Black powder fouled rifled barrels quickly, though, and its smoke hid distant targets, so rifles long remained tools of sharpshooters and hunters.
In colonial Pennsylvania, German and Swiss immigrant gunsmiths developed the long rifle before 1740; Jacob Dickert made an early one. Its tight bore, smaller balls and long barrel, which gave the burning powder more time to accelerate the shot, made it far more precise than the standard Brown Bess musket. Congress authorised ten companies of riflemen during the Revolutionary War, and Daniel Morgan's sharpshooters proved vital at Saratoga and Cowpens by targeting officers and artillery crews.
Modern rifles are classed as single-shot, bolt-action, semi-automatic or automatic, and only the last can fire more than one round per trigger pull. Automatic rifles differ from machine guns in being lighter, magazine-fed rather than belt-fed, and fired from a closed bolt for accuracy, which means they overheat too quickly for sustained fire. Air rifles use compressed air instead of powder and are popular for target shooting and pest control.
Source: Rifle
