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HEADSPACE...


DDRode

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I've built around a dozen 5.56 ARs, so I decided that it was time to build a .308 AR...

SO...

I picked up a AERO PRECISION Builders Set (M5E1)...

AND...

Purchased a FAXON 18" Pencil Barrel & a BROWNELLS 308AR Bolt Carrier Group from BROWNELLS!!!

I checked headspace (using finger pressure only) with FORSTER GO (1.630), NO GO (1.634), & FIELD (1.638) gauges!!!

I did not remove the EXTRACTOR or EJECTOR prior to checking headspace (since I don't have the tool to remove the EJECTOR)!!!

The bolt closed, rotated, and locked on both the GO & NO GO gauges, BUT did not close, rotate, or lock on the FIELD gauge!!!

I e-mailed  FAXON (Mark in Customer Service) who responded:

"We use Pacific Tool and Gauge reamers and gauges. The best thing to do is use their go and no-go gauges. We have noticed a variation between manufacturers gauges and attribute the issue to that. The fact that it closes on the field indicates it is safe to shoot, however, a field gauge is not meant to be used on a new barrel."

I also contacted BROWNELLS Tech Dept who said that the weapon would be safe to shoot as long as it passed with the FIELD gauge!!!

Any opinions???

http://faxonfirearms.com/18-pencil-308-win-rifle-length-4150-nitride/ 

https://www.brownells.com/rifle-parts/bolt-parts/bolt-carrier-groups/308ar-bolt-carrier-group-nitride-mp-prod105380.aspx?avs|Cartridge_1=CTT_308%2bWinchester

 

Edited by DDRode
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Get or make the tools to take out the ejector for headspace check. I like Pacific Tool and Gauge but would feel much more comfortable if the rifle passes with the Forster as well. Do you know anyplace you could get another bolt to check with the barrel?

Edited by jtallen83
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So you're sayin' that the fellas at FAXON & BROWNELLS are blowin' smoke outta their posteriors!!!

I've built at least two dozen M1 GARANDS at one time or another and checked headspace with and without the ejector and extractor in place...and it's made nary a difference!!!

My only real worry was that they passed with the FIELD gauge!!!

Is it that much more critical with .308 ARS than with 5.56 ARs or M1 GARANDS???

And other than buying another bolt (and that's outta the question)...I have no other bolts to check it with!!!

And I just popped the FORSTER gauges back in the mail to the feller I borrowed 'em from!!!

 

 

 

Edited by DDRode
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DD   Screw the head space gauges.....here's the best way to test your piece. Go to your local rifle range...Im sure you have one with an Ahole range officer that knows everything and treats everyone like crap? So you go there get your table all set up and then go tell the range officer you know nothing about this weapon and would he show you how to use it ?...He will be more than happy to fire your rifle for you....just stand a few feet behind him on the first shot....:laffs:  Wash

we have had folks post with the same exact problem.....and getting mostly the same answers from the mfg......go shoot the rifle

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This is the latest from MARK at FAXON Customer Service (12/28/2017)...

There is a big difference in standardization between the AR15 and Ar10 platforms. Because of that difference, I recommended using the gauges for the tooling we use. We have run into this numerous times with both Clymer and Forster gauges. Not that they make bad parts, but there is a slight difference, and with the possible tolerance stacking because of the lack of standardization the only way to assure proper headspace checking is to use the PTG gauges. I feel that with a pass using the Forster field gauge that the firearm is safe to shoot.

And this is from AR15.COM:

Posted: 1/31/2016 1:37:27 PM EST
[Last Edit: 1/31/2016 1:40:16 PM EST by RogueNathan]
Originally Posted By Vicious_138:
I have finally gathered all of my 308 build parts, so I took my bolt and barrel to a gunsmith to check my headspace.

I have an 18" Faxon barrel & an AIM nitride BCG. I removed the extractor and ejector before heading to the gunsmith. The bolt easily closed and locked on the go gauge, so then he tried the no-go gauge. The bolt closed and locked on the no-go, you could even wiggle the bolt a little while it was locked. Not good

My smith didn't have a field gauge, but he did the scotch tape trick on the no-go gauge. The bolt would not lock with the tape on the no-go gauge.
He then measured the bolt from the front of the lugs to the bolt face, and it was a consistent 0.125. I don't know know if this is what it should be or not.
Unfortunately I do not have another 308 bolt to check. So something is out of spec, but I don't know which.

I have emails out to both Faxon & AIM, so I will update with responses. Hopefully I can get this taken care of soon, it has taken me a while to get all the parts together, and now I am anxious to get it done. This is also being built on an 80% Arms 80% lower.


There are a few things that it could be related to, of which one of them not mentioned is the depth of the lugs themselves on the bolt, which is also a component.

The crazy part of the AR-15 & AR-10 specification is that there is only .003" from "Go" to "No-Go" and .005" total allowed deviation on the length of the bolt lugs itself (which does not account for the depth of the co-bore, which also has allowable deviation). All combined, this is what necessitates the need to head-space individual bolts to barrels.

We machine and check for head-space using tool steel bolts that we custom ground (the most accurate form of machining, outside of EDM) to check the head-space. Generally, this gives us confidence the barrel is not the issue

My assumption is that you are seeing tolerance stack between the bolt, co-bore, chamber depth, etc. This is common throughout AR's. The recommended solution is assuming the chamber is correct (we are making that assumption based on our quality procedures), a simple swap of the bolt closer to its nominal spec will bring you into nominal overall.

Given it does not rotate with scotch tape, you are at least .008" from field which is safe and serviceable (the rifling will wear prior to the chamber going out of spec), should you choose to keep the parts combination as stated.

Last piece to ask of a gunsmith is that they are using .308 WIN head-space gauges instead of 7.62x51 and the printed length on the gauge?

**OOPS! Noticed it was .308, which is also the same general facts. Posted updated to reflect the differences.
The Director at Faxon Firearms

Ask us any questions or drop me an e-mail: Nathan@FaxonFirearms.com
 

 

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  I can tell you the Brand or manufacturer of the Gages make a difference , we have seen it here where some have tried not only two sets of the same manufacturers HS Gages & another brand then what Faxon uses & had the same results you are getting , but the HS passed with the PT&G . 

  If you have a hybrid Chamber , good luck on any std HS Gage set working the way you want or expect . Doesn't mean they are unserviceable , just the Barrel manufacturer has custom HS Gages they use .

  In most cases Hs is done with out the Ejector ( because it installs false pressure on the Bolt for testing ) & Extractor ( because it can inferrer with the test also , by putting sideward pressure on the Gage , even if there is cut out on the gage for it ) Not all 308 Extractors are made with the same dimensional characteristics " Tolerance Stacking " something you see a lot in the non Mil Spec 308 AR's , but not in Factory Rifles or Mil Spec Rifles . Its just the way it is & I don't see any of the different manufacturers getting together to make all the components ," Mil Spec " or even some kind of factory spec .

  I test mine with the Bolt & Extension Dry ( oiled but wiped off ), no Ejector or Extractor & I test ,both before the Barrel is installed & after the Barrel is installed on the Receiver .

Edited by survivalshop
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12 hours ago, DDRode said:

"We use Pacific Tool and Gauge reamers and gauges. The best thing to do is use their go and no-go gauges. We have noticed a variation between manufacturers gauges and attribute the issue to that. The fact that it closes on the field indicates it is safe to shoot, however, a field gauge is not meant to be used on a new barrel."

This quote is from your first post.  This information is NOT correct.  If you ever have anything that CLOSES ON THE FIELD GAUGE, then that is NOT safe to shoot.  At all.  No way.

I don't know if you typed it up wrong, or what, but I can't imagine Faxon telling anybody that.

The Field gauge is the last resort, and it's usually only used on in-service weapons.  Most firearms should headspace on the Go gauge, not close on the No-Go.  Some might close on the No-Go.  After higher round counts, some weapons might now close on a No-Go gauge - and that is when you resort to the Field gauge.  If it still passes on the Field (does NOT close on it), then that weapon is still serviceable, but your accuracy might suck.   

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20 hours ago, DDRode said:

The bolt closed, rotated, and locked on both the GO & NO GO gauges, BUT did not close, rotate, or lock on the FIELD gauge!!!

  98

    I think the quote you posted is from Faxon Barrels ( I think ) & my take was his testing was posted above , that the Bolt did not close on the Field Gage . 

 
Edited by survivalshop
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8 hours ago, 98Z5V said:

This quote is from your first post.  This information is NOT correct.  If you ever have anything that CLOSES ON THE FIELD GAUGE, then that is NOT safe to shoot.  At all.  No way.

I don't know if you typed it up wrong, or what, but I can't imagine Faxon telling anybody that.

The Field gauge is the last resort, and it's usually only used on in-service weapons.  Most firearms should headspace on the Go gauge, not close on the No-Go.  Some might close on the No-Go.  After higher round counts, some weapons might now close on a No-Go gauge - and that is when you resort to the Field gauge.  If it still passes on the Field (does NOT close on it), then that weapon is still serviceable, but your accuracy might suck.   

I didn't type it...I merely copied it!!!

I'm sorry that it's beyond your imagination that someone at FAXON might type that by mistake!!!

BUT...

He obviously did!!!

Thanks for pointing that out...cuz I read it the way he meant it!!!

Anyway...

Mark in FAXON Customer Service is gonna take care of all my concerns...as a courtesy!!!

 

 

 

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5 minutes ago, DDRode said:

I didn't type it...I merely copied it!!!

I'm sorry that it's beyond your imagination that someone at FAXON might type that by mistake!!!

BUT...

He obviously did!!!

Thanks for pointing that out...cuz I read it the way he meant it!!!

Don't be sorry!!!

It's not "beyond my imagination"!!!

Faxon is filled with smart people, and it's hard to believe that would be sent to you, as obviously wrong as it is!!!

People often come here with issues, then don't describe them accurately!!! 

If you knew how to use the gauges, then you would have known about the statement on the FIeld gauge in the first place!!!

(Don't get all butthurt and upset at my writing style in this response!!!  All I did was match your style throughout your posts here!!!)

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Just now, 98Z5V said:

Don't be sorry!!!

It's not "beyond my imagination"!!!

Faxon is filled with smart people, and it's hard to believe that would be sent to you, as obviously wrong as it is!!!

People often come here with issues, then don't describe them accurately!!! 

If you knew how to use the gauges, then you would have known about the statement on the FIeld gauge in the first place!!!

(Don't get all butthurt and upset at my writing style in this response!!!  All I did was match your style throughout your posts here!!!)

I know the purpose of the FIELD GAUGE!!!

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22 hours ago, DDRode said:

So you're sayin' that the fellas at FAXON & BROWNELLS are blowin' smoke outta their posteriors!!!

I've built at least two dozen M1 GARANDS at one time or another and checked headspace with and without the ejector and extractor in place...and it's made nary a difference!!!

My only real worry was that they passed with the FIELD gauge!!!

Is it that much more critical with .308 ARS than with 5.56 ARs or M1 GARANDS???

And other than buying another bolt (and that's outta the question)...I have no other bolts to check it with!!!

And I just popped the FORSTER gauges back in the mail to the feller I borrowed 'em from!!!

 

 

 

My question is what the hell is an experienced builder of many ARs and Garands using that script font on a gun forum site anyway? 

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22 hours ago, DDRode said:

I've built at least two dozen M1 GARANDS at one time or another and checked headspace with and without the ejector and extractor in place...and it's made nary a difference!!!

Doing something wrong numerous times and getting away with it is far from making it right. You are a big boy and have every right to risk your own arse. My concern is other inexperienced builders reading this and thinking it is OK to check headspace with the extractor and ejector in place or thinking the field gauge is a good enough check and then hurting themselves. Granted it is a slim chance but these protocols have evolved over the years for a reason. If people pointing out little details like this bothers you then you may be in the wrong place.................

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34 minutes ago, DDRode said:

ADMINISTRATOR:

Close This Thread & Terminate My Membership!!!

These Are The Unfriendliest Bastards I've Ever Come Across On any FORUM Anywhere!!!

Unfriendly?.......

Well $hidt, just when it was getting interesting, even before we had our " Come to Jesus meeting" he bails out, counted to two and pulled the trigger.  

Edited by mrmackc
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Nah, we will keep this open and terminate you. This is part of what we represent. Helping people through their issues with build and understanding terminology. Your post is full of good info for others to learn from even if you don’t. Fax on is an outstanding company and there’s no doubt they will make things right. 

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My issue is... how old is your gripe? You posted a respond from “Nathan” who is a personal contact of mine. A guy who’ve I’ve spent countless amounts of time talking with on the phone. A guy who has been working for HK-USA for MONTHS and has NOTHING to do with Faxon. 

Brownells has a lifetime guarantee. Why was the bolt not returned and replaced?

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