Headspace issues

[drob]

Hi horde,

I'm doing my first 6.5 Grendel build with a Faxon gunner barrel (https://www.brownells.com/rifle-part...?sku=100026119) and a Brownell's BCG (https://www.brownells.com/rifle-part...?sku=078102006). I have Manson GO/NO-GO gauges (https://www.brownells.com/gunsmith-t...sku=513000101#). I'm finding that the bolt won't close on the GO gauge.

So, my question is, what next? What's the best way to diagnose whether I have an issue with my BCG or the barrel, or both?

Unfortunately, I didn't do the check earlier in the build. I have the upper receiver attached to the barrel, and the gas block and flash suppressor attached. Ideally, I wouldn't have to strip everything back again, but if that's the best way to go about it, that's fine, too.

Any advice would be appreciated. To be clear, both the BCG and the barrel should conform to 0.136" bolt face depth (per the descriptions). Whether they actual conform or not is up for debate at this point.

[A5BLASTER]

Not sure what the BCG has to do with headspace. Just the bolt does.

Do you have a second bolt to try? If not maybe get with brownells and see if you can send that one back for a replacment and retest.

If it does it again then it's the barrel is out of spec.

Or you can buy one of the group buy bolts off this site and see if it works, if it does then the brownells bolt is probably out of spec.

[A5BLASTER]

Also pull the BCG out and try the thump and dump test with a live round.

Drop a live factory round in and use your finger to make sure it's fully seated, turn the upper so the muzzle is pointed up and see if the round drops out. If it doesn't give the upper a few wackos each one harder if it takes several hard wackos are you have to use a cleaning rod to get it out. Send the barrel back for a replacment.

[drob]

Not sure what the BCG has to do with headspace. Just the bolt does.

Do you have a second bolt to try? If not maybe get with brownells and see if you can send that one back for a replacment and retest.

If it does it again then it's the barrel is out of spec.

Or you can buy one of the group buy bolts off this site and see if it works, if it does then the brownells bolt is probably out of spec.

Right, only the bolt matters, but I ordered it as part of a whole BCG. Unfortunately, right now, I don't have a second bolt or barrel to try to determine which might be the one that's out of spec. I guess I'll have to tell my wife, that I need more parts.

[drob]

Also pull the BCG out and try the thump and dump test with a live round.

Drop a live factory round in and use your finger to make sure it's fully seated, turn the upper so the muzzle is pointed up and see if the round drops out. If it doesn't give the upper a few wackos each one harder if it takes several hard wackos are you have to use a cleaning rod to get it out. Send the barrel back for a replacment.

OK, thanks. I'll give this a try and see what happens.

[centerfire]

I know Manson provides a relief for the ejector but the bolt needs to be stripped. It's probably just as easy to remove the gas tube and unscrew the barrel nut as it is to fiddle with the bolt inside the receiver.

[BCHunter]

^^
The bolt needs the extractor and ejector removed when using the gauges. If this wasn't done it may be the problem

[VASCAR2]

I also suggest you clean the barrel and chamber to ensure there isn’t debris affecting the go gauge from seating.

[NugginFutz]

In addition to stripping the bolt, it would not hurt to re-check the bolt face depth to ensure they actually sold a .136" depth bolt to you, and not the .125" variant.