Headspacing is to short?

ShaggySDG · Dec 17, 2016

Hello, I had completed my own custom AR-15 build and when I went to check the headspacing with the 5.56 gauge the bolt would not go into battery. I have a failzero BCG and a DEZ Arms barrel, I had called text support at Des Arms and the gentleman told me that scene it had a Nitro carburized finish that the chamber had to be polished before use (something like that). I wanted to see if this information was correct or if he is just screwing with me, This is my first build so I don't have to much knowledge on the subject, if this is true how do I go about polishing the chamber. I'm at a stand still and don't know what to do, so any advice is appreciated, Thanks.

omegared24 · Dec 17, 2016

Do you have access to another BCG to try? I've assembled several uppers and use standard phosphate BCGs with no problems at all.

Where are you located?

iH8DemLibz · Dec 17, 2016

Did you disassemble the bolt and clean the chamber (Protective Coating) prior to checking the head space?

ShaggySDG · Dec 17, 2016

omegared24 said:
Do you have access to another BCG to try? I've assembled several uppers and use standard phosphate BCGs with no problems at all.

Where are you located?

No, this is my first build and im in Baltimore, Essex.

iH8DemLibz said:
Did you disassemble the bolt and clean the chamber (Protective Coating) prior to checking the head space?

I had used a wire push rod and attached it to my drill to make sure it was clean, was a lot dirtier than I expected.
EDIT: I had taken the barrel back off and dissembled the firing pin and the extractor (ejector was to difficult to be honest) and tried the headspacing again making sure that the ejector was getting depressed.

outrider58 · Dec 17, 2016

I've bought a couple of their nytro carburised barrels and never had to clean or polish the chambers. This is a DEZ Arms barrel?

ShaggySDG · Dec 17, 2016

outrider58 said:
I've bought a couple of their nytro carburised barrels and never had to clean or polish the chambers. This is a DEZ Arms barrel?

Correct, AR-15 5.56 match barrel

2A Maryland · Dec 17, 2016

Head space issue

It is also possible that the extractor claw is stuck and the bolt won't go into battery because the extractor claw did not slip over the head of the case and into the extractor groove.

Try removing the bolt and carefully tapping out the pin that holds the extractor - be careful here that don't lose the spring that is under the extractor to the rear of the pin.

Re-install the bolt into the carrier and reassemble the the rifle. If the bolt goes into battery, the problem is not with the chamber. DO NOT USE A LIVE ROUND WHEN DOING THIS!

Another caution, be sure the cartridge case and the barrel are for the same ammunition. Sounds is bit silly, but these things do happen.

Also, if you are using a spent case from another rifle for testing, it could be that the barrel you are using has a tight chamber (sized to minimum specs) and the spent case was fired in a rifle with a loose chamber and needs to be resized to factory specs. I reload and have many resized empty 5.56 cases both commercial and military spec. Let me know if you need some. jhjosselyn@2AMaryland.org

ShaggySDG · Dec 17, 2016

2A Maryland said:
It is possible that the extractor claw is stuck and the bolt won't go into battery because the extractor claw did not slip over the head of the case and into the extractor groove.

Try removing the bolt and carefully tapping out the pin that holds the extractor - be careful here that don't lose the spring that is under the extractor to the rear of the pin.

Re-install the bolt into the carrier and reassemble the the rifle. If the bolt goes into battery, the problem is not with the chamber. DO NOT USE A LIVE ROUND WHEN DOING THIS!

Another caution, be sure the cartridge case and the barrel are for the same ammunition. Sounds is bit silly, but these things do happen.

I just tried to do this again and it still falls short, the gauge i'm using is the Forster 223 rem/556 NATO min (1.4636).

outrider58 · Dec 17, 2016

I would not recommend 'polishing' the chamber at all. The best thing you can do, as a novice in this case, is take it to a qualified gun smith who can check head space properly with go-nogo gauges and check other aspects of your build. It's the safest thing you can do. If a fellow member here could do that for you, that would be better than nothing.

lee2 · Dec 17, 2016

Since you're local, stop by blue fins on wise ave in Dundalk and have Dave check it out.

ShaggySDG · Dec 17, 2016

lee2 said:
Since you're local, stop by blue fins on wise ave in Dundalk and have Dave check it out.

Yea, seams that getting it checked out would be the best option.
Thanks

Pinecone · Dec 17, 2016

IIRC, according to Clandestine, you have to strip the bolt of the ejector and extractor to properly check headspace.

John from MD · Dec 17, 2016

I suggest that you check the headspace with a bare bolt. You can never get a good feel with a spring loaded ejector in the bolt. The ejector too, should be removed.

Just checking but you are using a "Go" gauge right?

clandestine · Dec 17, 2016

Very common, and I would venture to say the Bolt is the problem.

Here is a post I made about NiB Bolts.

https://www.mdshooters.com/showthread.php?t=196895

Polishing the chamber wont open up headspace, and it not something that should be done for headspace issues. The only time polishing a chamber is helpful is if your fired brass is frosty looking. That indicates of a rough chamber.

To open up headspace you try a different bolt. If that does not work the bolt has to be lapped to the barrel. That is NOT something for a novice.

Furthermore, that gage is on the .223 spec for a GO Gage. 5.56 GO is 1.4646. I suggest 1.4646 unless this is a match gun firing .223 ammo only.

clandestine · Dec 17, 2016

Pinecone said:
IIRC, according to Clandestine, you have to strip the bolt of the ejector and extractor to properly check headspace.

John from MD said:
I suggest that you check the headspace with a bare bolt. You can never get a good feel with a spring loaded ejector in the bolt. The ejector too, should be removed.

Just checking but you are using a "Go" gauge right?

This as well.

ShaggySDG · Dec 17, 2016

I had just got back from Blue Fins and Dave was vary informative and we tried 4 different BCG and only the broken BCG would properly close with the go gauge inside. We came to the conclusion that the barrel was bad so I had called Dez Arms back to tell them that we tested other BCG and that it still failed. They informed me that they use a different gauge with slightly tighter tolerances so mine would not fit. The gentleman insisted that I use live ammo and insert the bolt and see if it rotates freely. I will be revising ammo sometime next week so I have to wait until then.

I have tried to remove the ejector* multiple times, I can not every time it try to hammer it out the bolt slips out of the vice.

I am using the GO gauge as well, and if the bolt doesn't close on the smaller 223 (1.4636) gauge it will not close on the 556 (1.4646) one, but I understand what you are saying.

clandestine · Dec 17, 2016

ShaggySDG said:
I had just got back from Blue Fins and Dave was vary informative and we tried 4 different BCG and only the broken BCG would properly close with the go gauge inside. We came to the conclusion that the barrel was bad so I had called Dez Arms back to tell them that we tested other BCG and that it still failed. They informed me that they use a different gauge with slightly tighter tolerances so mine would not fit. The gentleman insisted that I use live ammo and insert the bolt and see if it rotates freely. I will be revising ammo sometime next week so I have to wait until then.

I have tried to remove the extractor multiple times, I can not every time it try to hammer it out the bolt slips out of the vice.

I am using the GO gauge as well, and if the bolt doesn't close on the smaller 223 (1.4636) gauge it will not close on the 556 (1.4646) one, but I understand what you are saying.

Glad you found the problem. Im suprised it was the barrel, but then again nothing shocks me lately with AR Manufacturers.

Did you disassemble the other bolts (remove ejector and extractor) used to check headspace? If not gauges can give a false reading unless they are modified.

Its sad the manufacturer is telling you to use ammo instead of a gauge to test headspace.

The extractor should come out without the use of a vise. Sounds like they have an extractor o ring in there which will bump up the tension.

ShaggySDG · Dec 17, 2016

clandestine said:
Glad you found the problem. Im suprised it was the barrel, but then again nothing shocks me lately with AR Manufacturers.

Did you disassemble the other bolts (remove ejector and extractor) used to check headspace? If not gauges can give a false reading unless they are modified.

Its sad the manufacturer is telling you to use ammo instead of a gauge to test headspace.

The extractor should come out without the use of a vise. Sounds like they have an extractor o ring in there which will bump up the tension.

No we just slid the whole BCG inside and attempted to close it multiple times, he even got one of his own completed upper to just check it anyway.

And yes I have removed the extractor it was the ejector that is giving me a bunch of trouble to remove.

John from MD · Dec 17, 2016

I don't know what kind of jaws you have in your vise but here is a suggestion. Go to wall mart and buy 2 4 or 5 oz fishing sinkers. The teardrop kind or round kind work best. Next, beat the sinkers flat until they are about 1/16 to 1/8 inch thick. Bend them onto your vise jaws and tighten down. You won't hurt the bolt and it will be held tight enough to drive out the ejector pin.

There is a tool that you can buy to compress the ejector so it doesn't disappear when you drive out the pin but, if you are careful, you can do without it.

Sticky · Dec 17, 2016

The ejector is tricky to remove (and reinstall, get a couple extra pins.. lol), but without Military gages that are modified to clear the ejector and extractor, they really should be removed before checking headspace.

Sounds like you are on to the issue, but I would still want my headspace to pass and I surely wouldn't test it with 556 ammo, only 223 til it passed the min 556 gage.

Headspacing is to short?

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