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Discussion Starter · #1 ·
Second AR build and I wanted to put the entire upper together myself this time rather than buy one already assembled...is the platform made to be operable by just putting the upper and barrel together without using headspace gauges, or does one need a headspace gauge for the process?
 

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If you're using a quality, trusted brand barrel and bolt, the headspace should be good.

It's a good idea to have the headspace checked with the appropriate gauges, for peace of mind.

But since the headspace is set by the barrel maker in the barrel extension, if the headspace is excessive, you're out of luck, if it's too short, you'll need a 'smith to adjust it with a chamber reamer.
 

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I would gauge it to be safe but my smith told me that usually a bolt and barrel of the same brand almost always are correct. different manufacturers may have different tolerances but usually not enough to be out of spec.
 

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Discussion Starter · #4 ·
Likely going to use Anderson as that is what all the parts are and my first one from them worked fine...think that should be ok?
 

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You should be just fine with Anderson components.
 

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While NORMALLY you MIGHT be OK with just building up an AR15 with random bolts and finished barrels, but are you willing to take that chance? I for one find it amazing that so many people take such unnecessary risks. Here is why.

First of all you are dealing with civilian manufactures who probably sold you the stuff because you thought the price was right....or cheap. Then YOU build the rifle without understanding why some things are very important and not left to chance.

Get the three gages. Go, No Go, and Field. We used Seven gages to give you an idea. We had to know exactly. The M16 platform is very forgiving regarding finished head space. It actually likes and gets away with slightly loose head space.

But....you need to know exactly. Odds? Very low actually. Very non likely of some sort of nasty stuff happening that may led to injury. IF you insist on building your own AR15, a helpful hint here would be to ask the provider if the head space is OK.

If your provider can guarantee proper head space with the provided bolt and barrel, then you are good to go. But....they can not or will not do such, get the three gages. You can swap them around later. Multiple uses are fine. They do not wear out.

Hope this helps kinda maybe. HB of CJ (old coot) (hundreds of AR builds) (torquing up the barrel properly with exact index is the most time consuming and important part of the build. With some knowledge and experience, it usually goes quite easy)

PEM if you want to. My job now is to pass stuff forward.
 

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Discussion Starter · #7 ·
Think I'll try to borrow the headspace gauges, shopped around and they seem expensive....around $75 right? Thanks for the info
 

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i've built a bunch of ars. if i thought i needed the gages, i'd buy them. i guess i'm just a risky guy. :cool:
 

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I've got several AR15. Several of them I built.

Only one gave me problems. One with a barrel and bolt bought from the same vendor/maker at the same time (my last AR15 build and the carbine that had everything on it I wanted). It would not chamber some rounds that worked fine in my other AR15's, it showed flattened primers, small crater walls around the firing pin indentation and blew a couple primers out of the cases (locked up pretty bad one time, had to remove the stock/tube and pound the bolt back with a steel cleaning rod/hammer till it got to the point where the primer fell out and the bolt feed up).

Anyway, got the headspace gauges. Laid you several AR15's and removed the bolts from each. Disassembled the bolts and checked headspace on each. On my carbine the go ga. would let the bolt close but there was no "play" at all. On the other ARs there was small amount of play, very small, but none of them would close the bolt on the field ga. so they were okay.

I had one rifle that was sloppy on the go ga. (but still wouldn't close on the field ga) so I swapped the bolts between that flat top A2 and the carbine (hated to do it because I had a chromed bolt in the new carbine) and the flat top rifles bolt gave me a little bit of play in the carbine (and the carbine bolt tightened up the slop on the go ga. in the A2).

No more chambering issues and no more blown primers.

No matter what people say, the parts that go together to build these rifles are made by people on machines that have worn parts. Machines wear out. Bearings, shafts, locks, threads, the tooling/cutters, etc. all wear and as they wear tolerances open up on the parts made with them. Even though the parts may be "in spec." when your luck results in you ending up with two (or more) parts that fit together that are "still in spec" you may have issues.

Its just a good idea to check.
 

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I've got several AR15. Several of them I built.

Only one gave me problems. One with a barrel and bolt bought from the same vendor/maker at the same time (my last AR15 build and the carbine that had everything on it I wanted). It would not chamber some rounds that worked fine in my other AR15's, it showed flattened primers, small crater walls around the firing pin indentation and blew a couple primers out of the cases (locked up pretty bad one time, had to remove the stock/tube and pound the bolt back with a steel cleaning rod/hammer till it got to the point where the primer fell out and the bolt feed up).

Anyway, got the headspace gauges. Laid you several AR15's and removed the bolts from each. Disassembled the bolts and checked headspace on each. On my carbine the go ga. would let the bolt close but there was no "play" at all. On the other ARs there was small amount of play, very small, but none of them would close the bolt on the field ga. so they were okay.

I had one rifle that was sloppy on the go ga. (but still wouldn't close on the field ga) so I swapped the bolts between that flat top A2 and the carbine (hated to do it because I had a chromed bolt in the new carbine) and the flat top rifles bolt gave me a little bit of play in the carbine (and the carbine bolt tightened up the slop on the go ga. in the A2).

No more chambering issues and no more blown primers.

No matter what people say, the parts that go together to build these rifles are made by people on machines that have worn parts. Machines wear out. Bearings, shafts, locks, threads, the tooling/cutters, etc. all wear and as they wear tolerances open up on the parts made with them. Even though the parts may be "in spec." when your luck results in you ending up with two (or more) parts that fit together that are "still in spec" you may have issues.

Its just a good idea to check.
Absolutely nothing wrong with checking. I'm just not going to do it. ;) Like I said, I'm a risky guy...that, and out of the thousands of posts I've read on forums like this, I've never seen a single post that indicated that there was an AR that malfunctioned because the barrel was improperly headspaced at the manufacturer.
 

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For a new build all you really need is one guage... the "No Go" gauge.
If the bolt closes on a "No Go" gauge your head space out of spec and you need to take it to a gun smith...

I will add this... I purchased a NiB BCG from Spikes Tactical/Fail Zero and I couldn't check the head space on my bolt because I couldn't get the roll pin out that retains the extraction plunger and spring. I have bent several roll pin punches trying to get it out and my guess is that they applied the NiB to the bolt after assembly... which is why I cannot get it out. I have not had any problems with any of my Parkerized bolts....
 

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Sorry about your extractor pin being stuck. Consider taking a properly sized small hard drill bit and cutting off the twist, turning it into a sacrificial expedient pin punch. Place the bolt head in a good vise and lock it down. The shorter the pin punch the better. Cheap pin punches are Chinese and very soft. Hard ones made in the USA are now impossible to find.

For what it is worth, ideally, the manufacturer should have chromed the individual parts. The extractor and pin should have been plated separately, then assembled. To do this correctly, the aforementioned individual parts must be acid etched just .005 of in inch. Then the plating brings them up to exact spec. They may not have done this, thus the parts are slightly over size.

Tear down the bolt and look. Tap out that pesky ejector roll pin. You might have to make a home made ejector lock down tool out of a handy small C clamp. Grind the C clamp end so it fits over the head of the bolt. Then lock down the ejector. The spring is quite springy. Consider a large Glad Bag containment sack. The ejector and roll pin should both be chromed.

Anyhow, another fun way to get that stuck extractor pin out. If you bolt works OK, then do not worry. You may just have a slightly oversize bolt, which actually is better. Tighter lock up. But...chrome is about .005 thick. I for one would be wondering what your installed head space will be. Just me. Hope this helps some. Passing it forward. HB of CJ (old coot)

PS: Forrester head space gages will tell you that you need to disassemble the extractor and perhaps the ejector from the bolt head. Not true. You can check head space on your assembled bolt with such gages because the back end is set up to slip over the extractor. The ejector head should compress will below the face of the bolt. Isn't this stuff fun?
 

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Ya, it's something everyone says you should do, but I never hear of any problems. Of course a "problem" could be catastrophic... but still. AR-15 are all mil spec. AR-10 are not. I built a .308 and always was going to check, but never did. I finally had to go to a gunsmith and had him check while he had it. It was all good. Reputable company.
 

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I have never headspace checked a AR15.

But i don't cut my own chambers either. The barrels I buy are all finished with extension installed. Most manufactures have a bolt in shop that they use to headspace with that is in spec. If you buy in spec parts, i don't see how there could be a problem.
 

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I have built several rifles, and have never checked the headspace. None have blown up and the reason why is i use parts from reputable companies that produce their parts within spec. or i am just lucky
 

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I have built several rifles, and have never checked the headspace. None have blown up and the reason why is i use parts from reputable companies that produce their parts within spec. or i am just lucky
I would agree with you, I have built close to a dozen and have had no issues. just buy from a reputable dealer.8)
 

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Discussion Starter · #17 ·
My major stuff is from Anderson (upper, lower, lpk) barrel is a new Wilson Combat and the other little parts are Brownells...not top of the line but decent I think. BCG is from Ares Armor (that cool nickel boron BCG they do).
 

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Go, no-go gauges are cheap, look cool on your coffee table and give you peace of mind on that barrel you picked up for dirt cheap at the gun show. Pick up a broken shell extractor at the same time and you'll thank yourself later since its a $5 part that can really save your butt.
 

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For what is may not be worth, about the only AR15s that are military spec are the older ones built as AR15s at Colt Industries on the military production line along side M16 rifles. Even then the Colt AR15 specific parts like the trigger, disconnecter and selector, etc., are NOT military spec, plus probably small parts.

If it is not a military or police issue Military contractor M16 rifle, which means most of the AR15 rifles out there, then most likely most or all of the parts may be military spec TYPE, but most certainly not military SPEC. Military spec means very expensive parts indeed, mostly not used by AR15 builders today.

If the part in question has a military contractor number and military part number, then it may be military spec. An example; only 14.5" GI barrels may be military spec. All civilian 16" barrels are most certainly NOT military spec. They may be military TYPE, but the manufacturing processes and quality controls may be different. Yep.

This specifically would also include AR15 triggers and selectors. (safeties) It is possible military spec M16 hammers are employed before modified to AR15 specifications, but maybe not either. Too expensive. Same thing with disconnecters. Too spendy. Military spec AR15 parts are very pricey to make and are quite rare.

Regarding head space gages. The three necessary gages are fairly cheap and are required for a proper build. This is why I do not shoot "home built" AR15 rifles. Why take the chance? It is a safety consideration. Kinda like brakes on an old car. Who did the work? Funny how we all take chances without knowing we do so. Yikes!

50,000 pounds of chamber pressure just inches from your face and eyes assembled by who know whom using whatever means from low end quality low price manufactures slapped together with no real knowledge/experience as to what can go wrong wrong with the build. That is the point I am trying to make. Yikes again!

HB of CJ (old coot) Trying to pass it forward. Have fun but keep it safe.
 

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For what is may not be worth, about the only AR15s that are military spec are the older ones built as AR15s at Colt Industries on the military production line along side M16 rifles. Even then the Colt AR15 specific parts like the trigger, disconnecter and selector, etc., are NOT military spec, plus probably small parts.

If it is not a military or police issue Military contractor M16 rifle, which means most of the AR15 rifles out there, then most likely most or all of the parts may be military spec TYPE, but most certainly not military SPEC. Military spec means very expensive parts indeed, mostly not used by AR15 builders today.

If the part in question has a military contractor number and military part number, then it may be military spec. An example; only 14.5" GI barrels may be military spec. All civilian 16" barrels are most certainly NOT military spec. They may be military TYPE, but the manufacturing processes and quality controls may be different. Yep.

This specifically would also include AR15 triggers and selectors. (safeties) It is possible military spec M16 hammers are employed before modified to AR15 specifications, but maybe not either. Too expensive. Same thing with disconnecters. Too spendy. Military spec AR15 parts are very pricey to make and are quite rare.

Regarding head space gages. The three necessary gages are fairly cheap and are required for a proper build. This is why I do not shoot "home built" AR15 rifles. Why take the chance? It is a safety consideration. Kinda like brakes on an old car. Who did the work? Funny how we all take chances without knowing we do so. Yikes!

50,000 pounds of chamber pressure just inches from your face and eyes assembled by who know whom using whatever means from low end quality low price manufactures slapped together with no real knowledge/experience as to what can go wrong wrong with the build. That is the point I am trying to make. Yikes again!

HB of CJ (old coot) Trying to pass it forward. Have fun but keep it safe.
most people don't cut their own chambers when building a rifle.

Also, there is a difference between Mil-Spec and procurement. the NSN numbers are there to identify specific vendor and model. Just because it's not in the database for purchasing does not mean it's not Mil-Spec.
 
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