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Hello all. I just finished a 24” 6.5 creedmoor dpms build and it won’t pass the 6.5 creedmoor go gauge headspace test. I took the bolt out of the BCG, removed the cotter pin. Removed the firing pin, cam, extractor and injector. I then replaced the cam, firing pin and cotter pin. I then replaced the bolt back into the BCG. Next, I slid the 6.5 creedmoor headspace go gauge into the barrel. I then took the BCG and proceeded to gently slide the charging handle and it through the upper towards the barrel. The bolt head seemed to not go all the way into the star chamber of the barrel. There was about a quarter inch protruding out of the back of the upper. However, it passed the snap cap function test numerous times. The action closes perfectly. When I charge it, the snap cap goes into the chamber, when I charge it again it ejects the snap cap and inserts the other one. When I pull the charging handle again it ejects the cap. But because it won’t pass the headspace test, I won’t feel safe firing it. I was told I should test it. Someone please advise, why won’t it pass headspacing, and is it safe to test it, since everything is new? Thank you.
 

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FYI...snapcaps have a purpose, function testing isn't it. 63,000 PSI, yeah, I wouldn't feel safe either.
You say "build", who assembled the barrel to receiver? If you bought it as a complete upper, it needs to be sent back. Correcting the headspace on an AR is complicated, and best left to a competent gunsmith.
 

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Stupid question but is your ammo factory new or reloads???

What is the OAL of the round and is that in spec with Loading manual data or COW limitations???

Are the primers seated to proper depth???

Whats the cartridge headstamp marked???

Let's cover the bases and rule out an ammo or reloading issue before tearing the gun to pieces...

IMHO.

Mike
 

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Stupid question but is your ammo factory new or reloads???

What is the OAL of the round and is that in spec with Loading manual data or COW limitations???

Are the primers seated to proper depth???

Whats the cartridge headstamp marked???

Let's cover the bases and rule out an ammo or reloading issue before tearing the gun to pieces...

IMHO.

Mike
His ammo has nothing to do with it.
Read what he posted he said he is using a "Go gage" that is NOT ammo. It is a gage that checks the head space.
@TRAPP55 is correct.
 

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You're sure it's a Go-Gage?
Do you have a piece of factory ammo on hand? Try that without the firing pin installed.
 
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His ammo has nothing to do with it.
Read what he posted he said he is using a "Go gage" that is NOT ammo. It is a gage that checks the head space.
@TRAPP55 is correct.
I understand that the rifle in question has not been fired - and that it passes a no go gauge check...

My possible concern was that while the rifle might spec out fine within acceptable parameters - that the ammo might be the problem rather then the rifle itself...

I recall personally having a carbine on what amounted to a pay as you go lay away - and that while I waited to take home the gun I ran some handloads up in a series of Lee single turret starter kit stations - only to discover that I when I brought the gun home I could not get the bolt to close on a round in the chamber...

OAL was a wee bit long and what seemed insignificant ended up being enough to impede the bolt from coming home and turning down...

I also have in mind a gent who showed up at the range with a new to him rifle - and he could not get the gun to feed or fire...

It turned out to be he had picked up .25-06 ammo and placed it in his range bag - he had brought his vintage .25 Remington rifle to the range to test fire...

Its incidents of that type that reminds me to check the ammo out first as the simplest factor to rule out prior to digging into the rifle itself for issues...

If that seems unnecessary to you or offends you or you feel an expert of your talent level need not be concerned with such basic possibilities so be it...

Personally I always look to rule out the possibility of the ammo being the issue prior to checking on the rifle itself.

KISS principle always applies IMHO.

But thanks for sharing - I feel all warm and fuzzy now.

Mike
 

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I understand that the rifle in question has not been fired - and that it passes a no go gauge check...

My possible concern was that while the rifle might spec out fine within acceptable parameters - that the ammo might be the problem rather then the rifle itself...

I recall personally having a carbine on what amounted to a pay as you go lay away - and that while I waited to take home the gun I ran some handloads up in a series of Lee single turret starter kit stations - only to discover that I when I brought the gun home I could not get the bolt to close on a round in the chamber...

OAL was a wee bit long and what seemed insignificant ended up being enough to impede the bolt from coming home and turning down...

I also have in mind a gent who showed up at the range with a new to him rifle - and he could not get the gun to feed or fire...

It turned out to be he had picked up .25-06 ammo and placed it in his range bag - he had brought his vintage .25 Remington rifle to the range to test fire...

Its incidents of that type that reminds me to check the ammo out first as the simplest factor to rule out prior to digging into the rifle itself for issues...

If that seems unnecessary to you or offends you or you feel an expert of your talent level need not be concerned with such basic possibilities so be it...

Personally I always look to rule out the possibility of the ammo being the issue prior to checking on the rifle itself.

KISS principle always applies IMHO.

But thanks for sharing - I feel all warm and fuzzy now.

Mike
I am not trying to be a PIA but you need to read what the poster said.
He said that IT DOSE NOT PASS THE GO GAGE.
AGAIN it has nothing to do with ammo.
He has NOT even put a round in it.
As I said @TRAPP55 is right THE HEAD SPACE IS OUT OF SPECS..........
AGAIN NO AMMO HAS BEEN PUT INTO THE GUN. JUST A GO GAGE AND IT DID NOT PASS THE TEST...........
TALKING ABOUT AMMO IS A WASTE OF THE POSTERS TIME (AND THOSE THAT READ THIS POST).
It has NOTHING to do with my expertise it has to do with what THE POSTER SAID but if you feel that ignoring the facts that the poster typed and want to go on about ammo story's just so you can post something which has NOTHING to do with the problem go on doing it.
Have a good day.
 

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Second motion of remove firing pin and use factory round.
I am just asking if you feel a no go gauge is not to be depended on?. I use them and would like to know if they are not accurate. And should not be depended on
 

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I am just asking if you feel a no go gauge is not to be depended on?. I use them and would like to know if they are not accurate. And should not be depended on
Mike, since I suggested using a piece of factory ammo, I will gladly give you my reasons. First, I know snap caps aren't precision, but they're close, and said it cycled them fine. Second, I think everyone that is going to assemble a barrel to a receiver should have a set of Go and No Go Gages. But, these are inspected and packaged by human beings. Who's to say that it wasn't marked and packaged incorrectly. Maybe he has a No Go Gage that was mis labeled or packaged. If a factory round goes fully into battery, I would be questioning the gage. With an AR platform, this issue could have been detected long before the barrel was assembled.
 
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Mike, since I suggested using a piece of factory ammo, I will gladly give you my reasons. First, I know snap caps aren't precision, but they're close, and said it cycled them fine. Second, I think everyone that is going to assemble a barrel to a receiver should have a set of Go and No Go Gages. But, these are inspected and packaged by human beings. Who's to say that it wasn't marked and packaged incorrectly. Maybe he has a No Go Gage that was mis labeled or packaged. If a factory round goes fully into battery, I would be questioning the gage. With an AR platform, this issue could have been detected long before the barrel was assembled.
Thank you. I will keep that in mind when I use them.
Again thank you.
 

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GUNZILLA
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Have you removed the extractor and ejector from the bolt? Once removed did you scrub the bolt clean, you must also scrub the chamber and lug recesses clean.
 
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From John's post, all new parts, and never been fired.
If the headspace gauges say it's out of spec, I fail to see what chambering a round accomplishes?, most guns out of spec will do that. Headspace gauges aren't something made in China that "almost works". I've used a lot of them in the last 45yrs, and have yet to use, see, or even heard of one that was out of spec. Way too much liability for a company to make one that was.
What am I missing here guys?
I'm still curious as to the "who" assembled the upper. In the last year with this panic buying demand, there have been frequent reports of barrels and uppers, that should never have been shipped, and headspace was a more common issue.
 

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My reasoning may be different from others but go/no-go`s fit a broad spectrum. A tight chamber could be the cause as this is a 6.5 Creedmore. A factory round might just fit. It`s a cheap-quick try without any downside.

and not riding the bolt forward.
 

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Gunzilla is correct, you have to remove the extractor and extractor spring from the bolt in order for it to check your headspace correctly. Brownells has some good video’s on it.

That’s how I checked my 6.5 CM, using a Wilson Combat Barrel, and Aeroprecision bolt.
 

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From John's post, all new parts, and never been fired.
If the headspace gauges say it's out of spec, I fail to see what chambering a round accomplishes?, most guns out of spec will do that. Headspace gauges aren't something made in China that "almost works". I've used a lot of them in the last 45yrs, and have yet to use, see, or even heard of one that was out of spec. Way too much liability for a company to make one that was.
What am I missing here guys?
I'm still curious as to the "who" assembled the upper. In the last year with this panic buying demand, there have been frequent reports of barrels and uppers, that should never have been shipped, and headspace was a more common issue.
I'm not a gunsmith, and don't pretend to be. But please be so kind as to read post #12.

There is human error factor in everything.
 

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Are you sure that the chamber is clean? Are you sure that you are using the go gauge and not the no-go? Are you sure you have the correct bolt? If the answer to all this is yes, I would assume you have a short chamber, or an incorrectly machined bolt. Do you have access to another bolt that you could try?
I've built 8 AR-15's. I had one that failed to headspace correctly, it was like the OP's, it would not chamber the go gauge. I tried it with 5 different bolts, none would chamber the gauge. All the bolts would chamber the go gauge in 4 different barrels. I decided it had to be the barrel, called and sent it back to the manufacturer, they sent me a new one. That's probably what you are going to have to do. If the manufacturer won't take it back, your only other choice would be to recut the chamber. That is possible since you seem to have a short chamber, unless you have a chrome lined barrel. If it were to long, you would be out of luck.
 

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From John's post, all new parts, and never been fired.
If the headspace gauges say it's out of spec, I fail to see what chambering a round accomplishes?, most guns out of spec will do that. Headspace gauges aren't something made in China that "almost works". I've used a lot of them in the last 45yrs, and have yet to use, see, or even heard of one that was out of spec. Way too much liability for a company to make one that was.
What am I missing here guys?
I'm still curious as to the "who" assembled the upper. In the last year with this panic buying demand, there have been frequent reports of barrels and uppers, that should never have been shipped, and headspace was a more common issue.
I agree, since everything is knew I was thinking maybe some packing lube was involved that got hard or machining slivers. When it comes to headspacing especially on AR platforms because parts can be interchangeable, which is great, still there could always be headspacing issues, especially if the bolt has not been matched to the barrel.
 
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