Quick Tip: How to Measure Barrel Length

Published on October 11, 2023
Duration: 7:37

This quick tip from Brownells demonstrates the proper method for measuring firearm barrel length, crucial for legal compliance and identification. The technique involves ensuring the firearm is unloaded and the action is closed, then using a cleaning rod or dowel to mark the barrel at the muzzle. Measuring from the bolt face to this mark provides the accurate barrel length as defined by the ATF.

Quick Summary

The ATF defines firearm barrel length as the measurement from the muzzle down to the breach face (the face of the bolt when the action is closed). To measure, ensure the firearm is unloaded, close the action, insert a rod to the bolt face, mark the rod at the muzzle, and measure the marked section with a tape measure.

Chapters

  1. 00:04Introduction to Measuring Barrel Length
  2. 00:14Example Firearms: AR-15 and Henry Lever Gun
  3. 00:25Step 1: Ensure Firearm is Unloaded
  4. 00:37Step 2: Close the Action
  5. 00:51ATF Definition of Barrel Length
  6. 01:04Required Tools for Measurement
  7. 01:10Using a Cleaning Rod for Measurement
  8. 01:25Using a Tape Measure and Sharpie
  9. 07:21Contacting the Tech Line for Help

Frequently Asked Questions

What is the ATF's definition of firearm barrel length?

The ATF defines firearm barrel length as the measurement from the muzzle of the barrel down to the breach face. This is the face of the bolt when the action is fully closed and locked.

What tools are needed to measure a firearm's barrel length?

You will need a cleaning rod or a similar straight object like a wooden dowel that fits inside the barrel. Additionally, a tape measure and a Sharpie marker are required to mark and measure the length accurately.

What is the first safety step before measuring a firearm's barrel length?

The absolute first and most critical safety step is to ensure the firearm is completely unloaded. Visually and physically inspect the chamber and magazine well to confirm there is no ammunition present.

How do you ensure an accurate barrel length measurement?

To ensure accuracy, close the firearm's action so the bolt is firmly against the chamber face. Then, insert a measuring rod until it contacts the bolt face, mark the rod at the muzzle, and measure the marked section.

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