How to Check Headspace on an AR-15

Larry Potterfield • August 24, 2023
Guns Gunsmithing

Before you attach a new barrel to your AR-15, it's important to check headspace. If the headspace isn't correct you need to fix it before proceeding.

Start with a stripped bolt. It needs to have both the extractor and ejector removed to prevent any false readings when using the headspace gauges.

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Stripped bolt by AR-15 barrel

A go and a no go gauge are needed for this process. The go gauge is sized to the minimum allowable headspace while the no go is over the max.

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A Go and No Go gauge

Because fouling brass shavings or other debris can affect the measurements, you must first clean the chamber thoroughly.

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Clean all debris out of barrel

Insert the go gage into the chamber.

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Go gauge goes first

Now slide the bolt into the barrel sleeve. You should be able to turn the bolt and engage the locking lugs completely. This lets us know that the chamber has at least a minimum amount of headspace.

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Bolt should turn

Now repeat the process using the no go gauge.

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No go gauge goes next

You should not be able to turn the locking lugs completely into battery.

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Bolt should not turn

If you can then you have excessive headspace and should not fire the gun. A different bolt may correct the problem. Otherwise, you'll need to replace the barrel. In either case, the gun must pass the headspace test!

--Larry Potterfield

Related Products

  1. Forster Headspace No-Go Gauge 223 Remington $37.19
  2. Forster Headspace Go Gauge 223 Remington $37.19
  3. AR-STONER Bolt Assembly AR-15 223 Remington, 5.56x45mm Matte $42.49
  4. Winchester 18-Piece Universal Rifle Gun Cleaning Kit $10.59
  5. Smith & Wesson M&P Compact Rifle Gun Cleaning Kit $45.19

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Larry Potterfield

Larry Potterfield is the Founder and Chairman of the Board of MidwayUSA. He and his wife Brenda, both country kids from Missouri, turned their passion for shooting sports into a career by opening a small gun shop in 1977 that would eventually become the industry-leading internet retailer it is today. For over 45 years, MidwayUSA has maintained an unyielding focus on Customer Satisfaction and continues to offer JUST ABOUT EVERYTHING® for Shooting, Hunting and the Outdoors.

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