Nearly all modern firearms have rifled barrels. Rifles, handguns (both pistols and revolvers), and most military weapons fire their projectiles through barrels with internal spiral grooves that spin the bullet for accuracy. The major exception is the shotgun, which typically uses a smooth, unrifled bore. Beyond that basic split, there are some interesting edge cases and historical context worth understanding.
Why Rifling Exists
Rifling consists of spiral-cut channels inside a barrel, creating raised areas called “lands” and recessed areas called “grooves.” As a bullet travels down the barrel, these features grip it and force it to spin. That spin creates gyroscopic stability, the same principle that keeps a football spiraling point-first through the air instead of tumbling end over end. Without it, a bullet would lose accuracy rapidly over distance.
The number of lands and grooves varies. Most barrels have four, six, or eight, though some specialty designs use as many as 20. Barrels with more than eight are sometimes called “microgroove” types. The most common setup places an equal number of lands and grooves arranged so that each land sits directly opposite another land.
Firearms That Have Rifled Barrels
Every standard rifle, pistol, and revolver sold today has a rifled barrel. This includes bolt-action hunting rifles, semi-automatic handguns, AR-platform rifles, lever-action carbines, and revolvers of all calibers. If it fires a single bullet (as opposed to shot pellets), it almost certainly has rifling.
Rifling is so fundamental to these categories that U.S. federal law builds its definitions around it. The Bureau of Alcohol, Tobacco, Firearms and Explosives defines a rifle as a shoulder-fired firearm that fires “a single projectile through a rifled barrel.” Pistols and revolvers are specifically noted as having “a rifled bore,” and any pistol or revolver without one falls into a separate, more heavily regulated legal category.
Two Main Styles of Rifling
Traditional rifling uses sharp-edged lands and grooves joined at roughly 90-degree angles. This is the “mil-spec” design found in most military and civilian rifles. It slightly deforms the bullet as it engages with the rifling, which is what creates the grip needed for spin. During World War II, Remington tested barrels with two grooves against barrels with four grooves in their 1903A3 rifles and found no meaningful difference in velocity or pressure between the two designs.
Polygonal rifling takes a different approach, replacing the sharp lands and grooves with a gentler “hills and valleys” profile. This style is produced through a cold hammer forging process and appears mostly in pistol barrels. Glock is the most well-known manufacturer using polygonal rifling. For years, advocates claimed it reduced bullet deformation, improved the gas seal behind the bullet, and increased velocity. More recent scientific testing has shown these benefits to be overstated: both styles perform roughly the same across the board. One genuine downside of polygonal rifling is that it doesn’t pair well with cast lead bullets, which can foul the barrel quickly and create dangerous pressure spikes.
Shotguns: The Smoothbore Standard
Shotguns are the clearest exception. A standard shotgun has a smooth bore with no rifling at all, which is ideal for firing shells loaded with multiple pellets. Rifling would cause the shot column to spin and scatter unpredictably, defeating the purpose of a spread pattern. Federal law defines a shotgun as a shoulder-fired weapon that fires “through a smooth bore.”
That said, rifled shotgun barrels do exist as a specialty option. These are almost exclusively used for firing sabot slugs, which are single projectiles wrapped in a plastic sleeve. The sleeve grips the rifling, picks up spin, and transfers that stability to the slug. If you’re hunting deer or other big game with a shotgun (often required by local regulations in certain areas), a rifled barrel paired with sabot slugs offers significantly better accuracy and range than a smoothbore firing standard slugs. One important note: rifled slugs, which have their own external grooves, are designed for smoothbore barrels. Despite the confusing name, you should not fire rifled slugs through a rifled barrel.
Military Weapons and Heavy Guns
Machine guns, sniper rifles, and most crew-served military weapons use rifled barrels. The same physics apply at larger scales: spin stabilization keeps the projectile on course.
Tank cannons are a notable exception. Most modern main battle tanks, including the U.S. M1 Abrams, the German Leopard 2, and the Russian T-90, use smoothbore guns. These fire fin-stabilized ammunition, where small fins on the projectile keep it stable in flight instead of barrel-induced spin. Smoothbore tank guns also suffer far less barrel wear than rifled designs, which matters when you’re firing high-velocity anti-armor rounds. The British Challenger 2 was one of the last holdouts using a rifled tank gun, though even the UK has moved toward smoothbore designs in its latest tank programs.
The Historical Shift From Smoothbore to Rifled
Rifling isn’t new. Historical documents describe rifled muskets as early as 1500, but the technology took centuries to become standard issue. The core problem was loading speed. Smoothbore muskets could be loaded quickly for the volley fire that European armies relied on, while rifles required more time because the ball had to be forced into the grooves. Speed mattered more than accuracy when armies were firing massed volleys at close range.
The American Revolution showcased what rifles could do in the right hands. While Washington’s regular troops carried flintlock smoothbore muskets, militia fighters used Pennsylvania long rifles to devastating effect at longer ranges. Still, rifles didn’t become general-issue military weapons until projectile design improved in the mid-1800s. The Minié ball, a bullet that expanded to grip the rifling on firing, finally solved the loading speed problem and made rifled muskets practical for mass armies. By the American Civil War, rifled barrels were standard on both sides.