Inside the barrel of a handgun or rifle, spiral grooves (referred to as barrel rifling) cause the bullet to spin. When the trigger is pulled, the primer is pounded and a spark is generated. This small explosion ignites the gun powder, resulting in the production of a large amount of gas and high pressure. Due to the high pressure, the bullet is forced out and passes through the barrel’s helical grooves. These spiral grooves, also referred to as barrel rifling, apply torque to the bullet, causing it to spin.

When fired from a rifle or handgun, bullets spin. What is the source of this spinning? Rifling is the answer. When bullets are fired from a rifle or handgun, barrel rifling causes them to spin. 

What Actually Causes Bullets Spin When Shot From a Rifle?

If you’ve seen the film Wanted, I’m sure you’ve noticed a scene in which a bullet begins to spin after being fired. 

Have you ever wondered why a bullet spins whenever a rifle or handgun is fired? Are all bullets spherical? Is this bullet spinning on purpose? 

Let us address each of these questions in turn. The answer to the first question, which is why bullets spin, is contained within the rifle’s barrel.

What Is Barrel Rifling?

If you cut the gun barrel, you will recognize that the internal surface of the barrel has helical grooves.


When the gun’s trigger is pulled, the primer is hammered, igniting it. The primer’s small explosion ignites the gunpowder in the case. When the gun powder is ignited, a large amount of gas is produced and a large amount of pressure is created, which forces the bullet out of one end of the cartridge. Then, the helical grooves within the barrel generate torque, compelling a bullet to spin along its longitudinal axis.

Rifling is the term used to describe the spiral grooves on the internal surface of the barrel. It is defined by its twist rate or the rate at which the rifle barrel spins. It indicates the distance traveled by the rifling during one complete revolution. Fast twist barrels are typically used with longer bullets, while slower twist barrels are typically used with shorter bullets.

Is it true that all bullets spin?

True, the majority of modern firearms incorporate spiral grooves that cause the bullet to spin. In Germany in 1498, barrel rifling was invented but did not become widespread until the nineteenth century due to the residue left by earlier gun powders quickly filling up these grooves and rendering them useless.

What is barrel rifling for?

Barrel rifling is used to improve the bullet’s accuracy and range. Due to the angular momentum gained during barrel rifling, a spinning bullet is more stable. In comparison to smoothbore barrels, it improves the bullet’s aerodynamic stability and accuracy.

What are the types of barrel rifling?

Historically, rifling consisted of sharp edge grooves. These sharp edge grooves are changed by less prominent “hills and valleys,” resulting in a polygonal barrel bore. 

Polygonal rifling has a number of advantages, including maintaining the barrel’s thickness, improving the gas seal around the projectile, reducing bullet deformation, increasing muzzle velocity, and extending barrel life.

This type of rifling is used in tanks and artillery pieces where the projectiles have small fins that ride in the barrel grooves. It contributes to the achievement of high muzzle velocity and range. South African G5 and Germany PzH 2000 are both examples of extended range full bore.

Barrels with gain twist rifling have a slowly increasing twist rate as the bore length increases. Gain twist rifling has been shown to improve accuracy and deliver more velocity when used with certain types of bullets and barrels.

Does the barrel length have an effect on the bullet’s spin rate?

The barrel length has no effect on the bullet’s spin rate. It contributes to the bullet’s velocity increase. The bullet’s spin rate is determined by the twist rate of the rifling. The bullet’s twist rate and velocity produce revolutions per minute (RPM), which aids in bullet stabilization. The revolutions per minute (RPM) of velocity can be calculated as

“Bullet RPM = Muzzle velocity x 720 / Twist Rate”

As a result, bullets spin when fired from a rifle or handgun due to barrel rifling.

🤔 What Is Barrel Rifling?

When the gun's trigger is pulled, the primer is hammered, igniting it. The primer's small ...

🔍 Is it true that all bullets spin?

True, the majority of modern firearms incorporate spiral grooves ...