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#2718332 - 09/09/14 09:49 AM ar15 headspace check
SlickerThanSnot Offline
PM senior

Registered: 01/31/14
Posts: 5957
Loc: stuck in a fence
to take the new shine off this forum.

skeptical is what i am when told there is a dead coyote in certain far off pictures.

#2781254 - 01/18/15 08:53 PM Re: ar15 headspace check [Re: SlickerThanSnot]
Raven One Offline
New Member

Registered: 01/18/15
Posts: 14
Loc: Arizona
This video is problematic shouldn't be held out as an example of how to properly verify headspace. It flat misses the mark. Just like a micrometer or electronic calipers, there's an art to taking a measurement with a headspace gauge. To specifically address the problems in the video, there are two issues that stand out. To properly and accurately verify headspace:

1. The barrel should always be removed from the upper receiver.
2. In conjunction with the headspace gauge, a master bolt should be used to verify headspace.

There are three parts that form the chamber on an AR-15 pattern rifle. The barrel, barrel extension and bolt. Using a used bolt to verify headspace, as is done in the video, doesn't eliminate the bolt as a source of an out of spec reading. Using a max reject gauge to verify service life of a barrel is the only gauging I subscribe to. The go / no-go gauging is realistically a manufacturing quality assurance process and really has to be done before the gas port is drilled. It's gonna be expensive to try and repair a new barrel that actually fails gauging.


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