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5.56 headspace issue


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I build my first 3 gun AR about a year ago and I am just finishing my second one. I read about Ar headspacing during my first build and never check it. I function tested everything and all was well. Gun operated just fine for the 700-1,000 rounds I have had through it. On this most recent build I let some forum talk get the best of me and I decided to test the headspace so I ordered Brownell's .223 Go?No Go gauges and a Forster 5.56 minimum gauge.

I have 2 completed ARs, one is a factory stock Remington R-15 in .223 rem and the other is my 3 gun AR that I built with a 5.56 NATO barrel. I did my headspace check on the R-15 and was fine. Did it on the AR I built with a Rainier Arms barrel in 5.56 and the bolt would not close on the GO gauge in .223 or the minimum 5.56 gauge.

Is this something I should worry about? Should I send this back to Rainier? Like I mentioned before, I have fired this several hundred times without incident. Now my brain is freaking out saying that this is an unsafe weapon.

Any and all advice would be greatly appreciated.

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Did you remove the ejector before checking the headspace?

Yes, all things considered a bit too short on the headspace (per the GO gauge) is going to be OK if the gun chambers and functions the ammo you choose

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The design of the gage determines whether you have to remove the ejector. Generally, military gages work with the ejector installed, whereas civilian gages require the ejector to be removed for an accurate reading. I actually modified my Forster FIELD gage to work with a compete bolt by grinding on it to clear the ejector and extractor:


Edited by StealthyBlagga
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