Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis. This spin serves to gyroscopically stabilize the projectile, improving its aerodynamic stability and accuracy.

Rifling is often described by its twist rate, which indicates the distance the bullet must travel to complete one full revolution, such as "1 turn in 10 inches" (1:10 inches), or "1 turn in 254 mm" (1:254 mm). A shorter distance indicates a "faster" twist, meaning that for a given velocity the projectile will be rotating at a higher spin rate.

The combination of length, weight and shape of a projectile determines the twist rate needed to stabilize it – barrels intended for short, large-diameter projectiles like spherical lead balls require a very low twist rate, such as 1 turn in 48 inches (122 cm). Barrels intended for long, small-diameter bullets, such as the ultra-low-drag, 80-grain 0.223 inch bullets (5.2 g, 5.56 mm), use twist rates of 1 turn in 8 inches (20 cm) or faster.

In some cases, rifling will have twist rates that increase down the length of the barrel, called a gain twist or progressive twist; a twist rate that decreases from breech to muzzle is undesirable, as it cannot reliably stabilize the bullet as it travels down the bore. Extremely long projectiles such as flechettes may require impractically high twist rates; these projectiles must be inherently stable, and are often fired from a smoothbore barrel.

Read more about RiflingHistory, Manufacture, Construction and Operation, Fitting The Projectile To The Bore, Twist Rate

Other articles related to "rifling":

Polygonal Rifling
... Polygonal rifling ( /pəˈlɪɡənəl/) is a type of gun barrel rifling where the traditional lands and grooves are replaced by "hills and valleys" in a rounded polygonal pattern, usually a hexagon or octagon ... In the Glock pistol, for instance, octagonal rifling is used in the large diameter.45 ACP bore, which has a 11.23 mm (0.442 in) diameter, since it resembles a circle more closely than the hexagonal rifling used in ...
Glock-VBR 7.92 Pistol - Design Details - Barrel
... The hammer-forged barrel has a female type polygonal rifling with a right-hand twist ... of the round is not by conventional rifling, using lands and grooves, but rather through a polygonal profile consisting of a series of six or eight interconnected non-circular segments (only the.45ACP ... unusual instead of using a traditional broaching machine to cut the rifling into the bore, the Glock process involves beating a slowly rotating mandrel through the bore to obtain the hexagonal or polygonal ...
Rifling - Twist Rate - Bullet Revolutions Per Minute (rpm)
... The general formula for calculating the rpm of a rotating object may be written as where is the linear velocity of a point in the rotating object (in units of distance/minute) and C refers to the circumference of the circle that this measuring point performs around the axis of rotation ... For a bullet, the specific formula below uses the bullet's MV and the barrel's twist rate to calculate rotational speed MV(in fps) x (12/twist rate in inches) x 60 = Bullet rpm For example, a bullet with a muzzle velocity of 3050 ft/s fired from a barrel with a twist rate of 1 in 7-inch (180 mm) (e.g ...
M14 Rifle - Rifle Design - Rifling
... Standard M14 rifling has right-hand twist in 112 inches with 4 grooves. ...
Steyr GB - Development
... The rifling used in the Rogak version was a hybrid of polygonal rifling ... In fact, the rifling did not have standard lands and grooves, but was there nonetheless ... This unique rifling did not allow the gas to escape in front of the bullet, so even though it bled gas which lessened recoil, the velocity increased by almost 30% ...

Famous quotes containing the word rifling:

    Always polite, fastidiously dressed in a linen duster and mask, he used to leave behind facetious rhymes signed “Black Bart, Po—8,” in mail and express boxes after he had finished rifling them.
    —For the State of California, U.S. public relief program (1935-1943)