Rifling: What Is It? What Is The Purpose Of Rifling In A Gun?

Rifling refers to the spiral (helical) grooves that are cut or swagged on the internal surface (bore) of a gun barrel, which helps impart the spinning motion to a bullet when it’s fired. A spinning bullet is found to be more stable in its trajectory, and is therefore more accurate than a bullet that doesn’t spin.

Back when firearms were first introduced in the theater of warfare, combatants were content with the fact that they had a weapon in their hands that discharged small objects that could hurt – or at least maim or severely injure – their opponents from a few dozen yards. For instance, take the military guns from the Victorian era. They had exceptionally long barrels, their reloading procedure took a long time, and they jammed more frequently than they should have.

However, the most vexing aspect of those guns was their range. Combatants had to stand quite close to the enemy to be able to take an “effective” shot, which, as you can imagine, was not ideal in the midst of a battle. In order to fix that, two changes were made: one in the design of the bullet and the other in the barrel of the smoothbore guns.

A bullet has an inherently aerodynamic design; it’s basically a cylinder with a somewhat pointy top. Such a design makes a bullet’s trajectory smoother and more stable as it sails through the air.

Notice the aerodynamic design of a bullet.

However, for longer range and accuracy, a better design won’t help much, unless it’s supplemented by some physical force, such as angular momentum, which is imparted to the bullet by rifling.


Recommended Video for you:


What is Rifling?

Firearms (e.g., pistols, rifles, tank guns etc.) consist of a number of helical grooves on the internal surface of their barrel (bore). This is referred to as rifling. If you look down the barrel of a gun and observe closely, you will see a pattern like this engraved on the bore of the gun. This is not only present in regular guns; even tank guns have rifling in their barrels.

Conventional rifling of a 90 mm M75 cannon

Rifling of a M75 cannon (Photo Credit : Petar Milošević / Wikimedia Commons)

What is the purpose of rifling in a gun?

Rifling imparts spin to the bullet along the latter’s lengthwise axis. This helps the bullet maintain a stable trajectory when it leaves the gun and enhances both the range and target accuracy of the gun. That’s the short answer.

But how does spinning the bullet help improve its stability during flight?

Two words – angular momentum.

Angular momentum, in essence, is the ‘quantity’ of rotation in a body. Just as a body moving linearly (i.e., along a straight line) has linear momentum, a rotating body has angular momentum.

The best example of angular momentum in action is a spinning top.

Spinning top

A spinning top aptly illustrates the massive role angular momentum plays in maintaining a body’s spinning motion. (Photo Credit : David Earle / Wikimedia Commons)

You have likely noticed that a spinning top, especially a fast-moving one, doesn’t fall over easily, even when you give it a little nudge. The only change that you may notice after nudging a spinning top is that it starts describing a little circle with its tip. This is called precessing.

Gyroscope precession

Precession on a gyroscope. ( Photo Credit : LucasVB / Wikimedia Commons)

Precession helps a fired bullet continue straight in the direction in which it was shot, rather than cartwheeling end over end. Moreover, the spin imparted to it with the help of the rifling keeps it going along its original course with nothing more than a little wobble. Had there been no rifling in the gun (as was the case in primitive smooth bore rifles), then the fired bullet would not spin and would consequently “tumble out” of its course pretty soon after emerging from the muzzle.

Bullets are made of a material (generally lead) that is softer than the bore’s material (typically steel). When the bullet is fired, a huge amount of pressure (more than 35,000 psi) builds up on the neck of the round. Since the bullet is usually the same diameter as the bore, it plugs the bore completely, pressing tightly against the internal surface of the barrel. As the bullet moves inside the barrel, it follows the helical grooves on the bore’s surface, and consequently, spins rapidly as it travels down the barrel.

In this way, a small structural change in the design of the barrel of guns made a massive impact on their range and performance that we still see to this day!

How much do you know about rifling?

Can you answer three questions based on the article you just read?

Suggested Reading

Was this article helpful?
YesNo
Help us make this article better

Follow ScienceABC on Social Media:

About the Author

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spearheads the content and editorial wing of ScienceABC and manages its official Youtube channel. He’s a Harry Potter fan and tries, in vain, to use spells and charms (Accio! [insert object name]) in real life to get things done. He totally gets why JRR Tolkien would create, from scratch, a language spoken by elves, and tries to bring the same passion in everything he does. A big admirer of Richard Feynman and Nikola Tesla, he obsesses over how thoroughly science dictates every aspect of life… in this universe, at least.

.
Science ABC YouTube Videos

  1. Slowing or Reversing Aging: Can We Live for 180 years?Slowing or Reversing Aging: Can We Live for 180 years?
  2. Detectives Use this Simple Technique to Find Your Fingerprints (Even AFTER You Have Wiped Them Off)!Detectives Use this Simple Technique to Find Your Fingerprints (Even AFTER You Have Wiped Them Off)!
  3. Why is a Circle 360 Degrees, Why Not a Simpler Number, like 100?Why is a Circle 360 Degrees, Why Not a Simpler Number, like 100?
  4. Quantum Physics: Here’s Why Movies Always Get It WrongQuantum Physics: Here’s Why Movies Always Get It Wrong
  5. Do Fish Get Thirsty and Do They Need to Drink Water?Do Fish Get Thirsty and Do They Need to Drink Water?
  6. Gasoline (Petrol) vs Diesel: Which one is better? A Beginner’s GuideGasoline (Petrol) vs Diesel: Which one is better? A Beginner’s Guide
  7. Black Holes Explained: What Is a Black Hole? How They Form?Black Holes Explained: What Is a Black Hole? How They Form?
  8. Gut Microbiome Explained in Simple WordsGut Microbiome Explained in Simple Words