Quick Tip: What's the Best Barrel Length for an AR-15?

Published on January 11, 2023
Duration: 7:04

Brownells experts Steve and Caleb provide a comprehensive guide to AR-15 barrel lengths, highlighting the 16-inch standard and the growing popularity of the 13.7-inch barrel for its balance of size and performance. They detail legal considerations for barrel length, such as pinning muzzle devices, and discuss the ballistic trade-offs associated with different lengths, emphasizing that beyond 18 inches, gains are minimal. The discussion also touches on how barrel thickness impacts accuracy through heat management and reduced whip.

Quick Summary

The 16-inch AR-15 barrel is a versatile standard, while the 13.7-inch offers a compact alternative, especially when legally extended with a pinned muzzle device. Barrels under 10.5 inches are not recommended for 5.56/.223 due to significant velocity loss and potential reliability issues. Beyond 18 inches, velocity gains are minimal for the added weight.

Chapters

  1. 00:00Introduction to AR-15 Barrel Lengths
  2. 00:4216-inch Standard vs. 13.7-inch
  3. 01:33Legal Length and Pinning Muzzle Devices
  4. 02:10Benefits of the 13.7-inch Build
  5. 03:34Short Barrel Limitations (10.5-inch and below)
  6. 04:35Long Barrel Diminishing Returns (18-inch to 24-inch)
  7. 05:54Barrel Thickness and Accuracy

Frequently Asked Questions

What is the best barrel length for an AR-15?

The 'best' AR-15 barrel length depends on your needs. A 16-inch barrel is a versatile standard, while a 13.7-inch barrel offers a compact option, especially when legally extended with a pinned muzzle device. Barrels shorter than 10.5 inches are generally not recommended for 5.56/.223 due to significant performance loss.

Can a 13.7-inch AR-15 barrel be legally considered a 16-inch barrel?

Yes, a 13.7-inch barrel can be legally compliant with the 16-inch minimum barrel length requirement for rifles. This is achieved by permanently attaching a muzzle device, such as a compensator or flash hider, via a pin and weld method, bringing the total barrel assembly length to 16 inches or more.

What are the downsides of very short AR-15 barrels (under 10.5 inches)?

Barrels shorter than 10.5 inches for 5.56/.223 cartridges lead to substantial reductions in muzzle velocity and energy. They can also cause gas system issues, making the firearm more finicky and less reliable. For most users, these drawbacks outweigh any perceived benefits of extreme compactness.

Does a longer AR-15 barrel always mean more accuracy?

Not necessarily. While longer barrels can increase velocity, accuracy is also heavily influenced by barrel thickness and heat management. A shorter, thicker barrel can be more accurate than a long, thin one because it experiences less 'barrel whip' and dissipates heat more effectively, maintaining stability during firing.

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