How to Measure Ar Barrel Length

To measure ar barrel length, use a measuring tool to determine the distance from the breach face to the muzzle. Measuring barrel length is important for determining firearm legality and performance.

The length of the barrel impacts factors such as accuracy, velocity, and recoil. In addition, certain laws place restrictions on barrel length for certain firearms. Measuring the barrel length ensures your firearm meets legal requirements and optimal performance.

How to Measure Ar Barrel Length


Understanding Your Ar Barrel

If you’re an ar enthusiast, you understand the importance of getting your barrel length just right. Choosing the correct ar barrel length is crucial, as it can affect your firearm’s accuracy, power, and performance. We’ll guide you through the basics of what you need to know about ar barrels and how to measure them accurately.

What Is An Ar Barrel?

The ar barrel is the long metallic tube that guides and contains the bullet as it leaves the firearm. The barrel is a crucial component of your firearm that can affect shot accuracy and other critical elements of shooting performance.

Here are a few essential points you need to know:

  • Ar barrel lengths vary between 7.5 inches to 24 inches.
  • Barrel length is measured from the chamber to the outer edge of the muzzle.
  • The barrel’s caliber is determined by the bullet’s diameter that the barrel can accommodate.
  • Different barrel types are optimized for specific purposes, and the barrel material can affect accuracy, weight, and heat dissipation.

How Does The Barrel Length Affect The Ar Performance?

The barrel length plays an important role in determining the firearm’s accuracy, power, and recoil. Here are some of the effects that different barrel lengths can have:

  • Longer barrels can lead to increased accuracy, as the bullet has more time to stabilize before it leaves the barrel. However, longer barrels may also reduce portability and maneuverability.
  • Shorter barrels tend to be more portable and maneuverable in tight spaces. However, they usually come at the expense of accuracy and power, as the bullet has less time to stabilize before it leaves the barrel.
  • Barrel length can also affect the firearm’s recoil. Shorter barrels tend to produce more recoil due to the higher-pressure build-up at the muzzle.

What Are The Different Ar Barrel Lengths Available In The Market?

Now that you understand how barrel length affects an ar rifle’s performance, it’s time to consider the available options in the market. The most common ar barrel lengths are:

  • 7.5 inches: The shortest barrel length for an ar rifle; designed primarily for close-quarter combat applications.
  • 10.5 inches: Slightly longer than the 7.5-inch barrel; optimized for mid-range shooting distances.
  • 16 inches: The most common barrel length designed for general-purpose shooting applications.
  • 18 to 20 inches: Used for long-range shooting applications due to increased accuracy.
  • 24 inches: Designed specifically for long-range target shooting.

Choosing the right ar barrel length is crucial for achieving optimal performance and accuracy. By understanding your firearm’s capabilities and using proper measurement techniques, you’ll be well on your way to a successful shooting experience.

Measuring Ar Barrel Length

The barrel length of your ar is an important factor in determining accuracy and recoil. Measuring the length of your ar barrel is a critical step that should be taken with proper tools and techniques. We’ll provide you with a step-by-step guide on how to measure ar barrel length and discuss potential issues you may encounter in the process.

Tools Required For Measuring The Ar Barrel Length

Before you start measuring your ar barrel length, ensure you have the following tools:

  • A caliper: This tool is used to measure the diameter or thickness of objects.
  • Measuring tape or ruler: Used to measure the overall length of the barrel.
  • Cleaning rod: A long, thin, and flexible rod used to clean the barrel.

Step-By-Step Guide To Measure Ar Barrel Length

Follow these steps for accurate measurement:

  • Ensure your ar is unloaded and cleared of ammunition.
  • Remove the bolt carrier group and any other attachments like muzzle devices.
  • Insert the cleaning rod through the barrel’s bore until you feel it touching the bolt face.
  • Make a mark on the cleaning rod at the end of the muzzle.
  • Remove the cleaning rod and measure its length from the mark made in step 4 to the end of the rod.
  • Use the caliper to measure the diameter of the barrel at the chamber end, and again at the muzzle end.
  • Add both measurements to get the average diameter.
  • Multiply the diameter by 3.14 (pi) to get the circumference.
  • Finally, measure the distance from the bolt face, located in the chamber, to the mark you made on the cleaning rod.

What Are Some Potential Issues That You May Encounter While Measuring The Ar Barrel Length?

Some of the potential issues you may encounter while measuring ar barrel length include getting inaccurate measurements when:

  • There is a muzzle device attached to your muzzle.
  • The cleaning rod is bent or warped.
  • The barrel is coated or has rust or debris inside.
  • The chamber is dirty or obstructed.

Measuring the ar barrel length is a straightforward process that requires a few specialized tools and following some simple steps. By taking accurate measurements, you can determine the optimal bullet weights, twists, and barrel lengths required to enhance your ar’s accuracy and performance.

Factors To Consider When Measuring Ar Barrel Length

Understanding The Difference Between The Nominal Length And The Actual Length

When measuring ar barrel length, it’s important to understand the difference between the nominal length and the actual length. The nominal length is the length of the barrel that is specified by the manufacturer, while the actual length is the length of the barrel from the face of the bolt to the end of the muzzle device.

Keep in mind that the actual length can be longer or shorter than the nominal length, depending on the measurement method used.

The Importance Of Taking Measurements From The Barrel Crown

When measuring ar barrel length, it’s essential to take measurements from the barrel crown. The crown is the end of the barrel that comes into contact with the bullet when fired. A damaged or improperly crowned barrel can affect accuracy, so it’s important to ensure that the crown is undamaged and properly aligned with the bore axis.

Barrel Extension And Its Impact On Barrel Length Measurement

The barrel extension is the part of the ar barrel assembly that houses the bolt carrier group. When measuring ar barrel length, it’s important to take into account the length of the barrel extension. Depending on the manufacturer, the barrel extension can add anywhere from 0.

6 to 1. 3 inches to the overall length of the barrel.

Ar Barrel Nut And Its Impact On Barrel Length Measurement

The ar barrel nut is the part of the barrel assembly that attaches the barrel to the upper receiver. When measuring ar barrel length, it’s important to take into account the length of the barrel nut. Depending on the manufacturer, the barrel nut can add anywhere from 0.

8 to 1. 3 inches to the overall length of the barrel.

Overall, when measuring ar barrel length, it’s important to take into account all the factors that can affect the measurement. Taking accurate measurements is essential for ensuring that the rifle is operating correctly and meets regulations.

Advantages And Disadvantages Of Different Ar Barrel Lengths

Barrel length can significantly impact the accuracy and overall performance of your ar, so it’s crucial to know how to measure it appropriately. But how do you determine the ideal barrel length for your ar? Understanding the advantages and disadvantages of various barrel lengths can help you make an informed decision.

Advantages & Disadvantages Of 16-Inch Barrel

A 16-inch barrel is a popular choice for those who use their ar for home defense, as it provides a good balance of muzzle velocity, maneuverability, and accuracy. However, there are both advantages and disadvantages of this barrel length:


  • Lightweight and maneuverable
  • Ideal for close quarters combat (cqc)
  • Easy to maneuver in tight spaces


  • Lower projectile velocity compared to longer barrel lengths
  • Reduced accuracy at longer ranges
  • Reduced capability to mount accessories and suppressors

Advantages & Disadvantages Of 18-Inch Barrel

The 18-inch barrel is another popular choice among ar enthusiasts, as it offers noticeable improvements in accuracy and velocity without compromising too much on maneuverability. Here are the main advantages and disadvantages:


  • Increased projectile velocity compared to 16-inch barrels, which means improved accuracy at longer ranges
  • Provides a better platform for mounting accessories and suppressors compared to shorter barrels
  • Offers excellent balance between maneuverability and velocity


  • Not as lightweight as 16-inch barrels
  • Can be challenging to maneuver in tight spaces

Advantages & Disadvantages Of 20-Inch Barrel

The 20-inch barrel is often used by the military and law enforcement agencies due to its exceptional accuracy and velocity. Here are the key advantages and disadvantages of this barrel length:


  • Provides excellent projectile velocity, which translates into exceptional accuracy at long ranges
  • Enables the use of bayonets and other accessories, making it ideal for military and law enforcement applications
  • Longer sight radius


  • Heavier and more cumbersome than shorter barrels
  • Not as maneuverable in close quarters combat (cqc)

Advantages & Disadvantages Of 24-Inch Barrel

The 24-inch barrel is the longest standard barrel for an ar and offers maximum velocity and accuracy at long ranges. It’s mainly used for long-range shooting, competitive shooting, and hunting. Here are the advantages and disadvantages of this barrel length:


  • Has the longest sight radius, which increases accuracy at long distances
  • Offers the highest projectile velocity and excellent accuracy at long ranges
  • Ideal for long-range competitive shooting and hunting


  • The longest and heaviest barrel, which restricts maneuverability
  • Not suitable for close-quarters combat

Your choice of ar barrel length will depend on your intended use of the firearm. Keep in mind that longer barrels generally offer improved accuracy and velocity, but are also heavier and less maneuverable. On the other hand, shorter barrels offer increased maneuverability but reduced accuracy and velocity at longer distances.

It’s essential to understand the advantages and disadvantages of different barrel lengths to make an informed decision that matches your shooting needs.

Frequently Asked Questions Of How To Measure Ar Barrel Length

How Do You Measure Barrel Length On An Ar?

To measure your ar barrel length, take a measuring tape and measure from the tip of the muzzle to the rear end of the receiver. It’s vital to ensure your barrel is legal before making any alterations to your rifle.

What Is The Legal Ar Barrel Length?

The legal ar-15 barrel length is determined by the national firearms act, which defines the minimum rifle barrel length as 16 inches. However, a barrel shorter than 16 inches can be used legally if it is registered with the atf.

What Happens If My Ar Barrel Is Too Short?

If your ar barrel is too short, it will make your firearm illegal and subject to immediate seizure by law enforcement. In addition, possessing a firearm with a barrel length that does not comply with federal law is a federal crime and can lead to severe penalties.

Is There A Difference Between Barrel Length And Overall Length?

Yes. Barrel length is the distance from the end of the muzzle to the rear edge of the chamber, while overall length is the firearm’s measurement from the tip of the barrel to the end of the stock. Compliance with the law is typically determined using barrel length.

Can I Modify My Ar Barrel Once It Is Measured?

Yes, you can modify your ar barrel length by having it cut or replaced by a knowledgeable gunsmith. However, be sure that the finished product complies with the minimum length requirements laid out by federal law. Remember that once a firearm is modified, it needs to be re-measured.


After reading this guide, you should now be able to accurately measure the barrel length of your ar-15 rifle. Remember to have the right tools on hand, take measurements at the proper points, and be consistent with your method. The accuracy of your measurement is crucial when selecting the appropriate gas system for your rifle.

Keep in mind that the longer the barrel, the more precise and consistent your shots will be at longer distances. So, it’s important to know the exact length of your ar barrel for both practical and legal reasons. With this knowledge, you can ensure that your rifle is functioning optimally, and you can obtain the best performance for your hunting or shooting needs.

Don’t hesitate to ask for help if you run into any issues along the way.

Leave a Comment