Headspacing on built rifle? (noob)

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Posted: 12/8/2014 6:43:17 AM EDT

Sincerest apologies if this is in the wrong place... I used the search function but didn't see anything really similar to my situation.

So, I built this mutt. I started off with a Colt 6720(?) pencil barrel that I picked up off a buddy and mated it to a generic upper reciever that I bought off of CDNN for like $40. I didn't have any problems lining up the barrel nut, nor getting the gas tube lined up or installed. It's got a DPMS bolt carrier assy that I also picked up off of CDNN ($100, I think). The rest is stuff from PSA, Spikes (purchased before I saw their rep acting like a world class jackass on here), headdown. It does have a Geissele SSA-E trigger and Diamond BUIS, which I'm pretty psyched about.

However, I've been thinking a lot about the headspacing lately. When I started building it, I read a lot of things which basically led me to believe that since the barrel had already been on another rifle (A colt) and fired, the headspacing would have been set already. However, since it's mated to another upper, do I need to have it checked? I haven't had a chance to fire it yet, so there's a modicum of concern there. Admittedly, I know very little about headspacing and would appreciate some solid input on my particular case.

In closing, I apologize sincerely for the redundant post. It's my first day. TIA!

Posted: 12/8/2014 7:18:47 AM EDT

[#1]

Aw geez. Found it. I jumped the gun. Derp derp derp

Posted: 12/8/2014 10:07:48 AM EDT

[#2]

Bolts have tolerances like barrels and anytime a change is made headspace should be checked.

Posted: 12/8/2014 12:36:28 PM EDT

[#3]

In the AR world, barrels are headspaced when the barrel extension is pinned, and given the tolerances allowed, work 98%+ with any bolt you mate it with.

It's the 2% we worry about and you can find posts were somebody ran into a situation. Thousands of barrels a year are sold without bolts, assembled, and the guns work fine.

I will go so far as to suggest that a lot of makers are not headspacing a specific bolt to that barrel in assembly. It's because Stoner designed the gun so that it can be done more easily without a gunsmith needing to be employed. Only during the barrel assembly getting the extension screwed on, like a micrometer, does the headspace get checked, and being an high tech aerospace engineer, he came up with a completely different method. Most other barrels are assembled by a press into a receiver with the specific bolt to do that operation.

AR's are not like other guns.

The barrel extension is something that makes it completely different, so methods familiar to the traditional smith don't apply. Like, bedding.

Since there is a 98%+ bias it's right, you could get it checked. Or, you could shoot it like most of us do.

Posted: 12/8/2014 2:52:51 PM EDT

[#4]

Just over $20.

http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/5-56mm-maximum-headspace-gauge-prod6646.aspx

Get a .223 SAAMI go-gage as well, which will probably set you back another $20.

I check every time I install a new barrel or bolt.

Posted: 12/8/2014 2:54:48 PM EDT

[#5]

The bolt and barrel extension are what determine the headspace. As another poster mentioned, most of the time the machining is accurate enough that the headspace will be good, so lots of people just put them together and shoot them and never have problems.
However, many of us check headspace routinely as part of the workflow, just to catch that rare one that is a problem.
Gauges are about $60 for a Go and a No Go gauge together. It should pass the Go and Fail the No Go.

Posted: 12/8/2014 3:37:39 PM EDT

[#6]

Quote History

Quoted:

In the AR world, barrels are headspaced when the barrel extension is pinned, and given the tolerances allowed, work 98%+ with any bolt you mate it with.
It's the 2% we worry about and you can find posts were somebody ran into a situation. Thousands of barrels a year are sold without bolts, assembled, and the guns work fine.
I will go so far as to suggest that a lot of makers are not headspacing a specific bolt to that barrel in assembly. It's because Stoner designed the gun so that it can be done more easily without a gunsmith needing to be employed. Only during the barrel assembly getting the extension screwed on, like a micrometer, does the headspace get checked, and being an high tech aerospace engineer, he came up with a completely different method. Most other barrels are assembled by a press into a receiver with the specific bolt to do that operation.
AR's are not like other guns.
The barrel extension is something that makes it completely different, so methods familiar to the traditional smith don't apply. Like, bedding.

Since there is a 98%+ bias it's right, you could get it checked. Or, you could shoot it like most of us do.

View Quote

Some points to be made here, but overall point of the post is somewhat dangerous. The headspace is measured from the datum line to bolt face. You cannot know the headspace without the exact bolt you are using. You can guess because parts are built within tolerances??? But which parts and which tolerances?? How do you know unless you measure, and the barrel manufacturer CANT measure that for you because in most cases they don't have your bolt. So generalities COULD POTENTIALLY work here.( i admit the percentages show they seem to, or barrels are simply built well enough to tolerate it--see shortened lifespan of barrel)

But I don't like it when people use phrases like that gun SHOULD be headspaced correctly. Or another similar phrase would be, That gun SHOULD be unloaded? When you put it into perspective using facts it doesn't sound so good. Guys like the poster quoted here can do whatever they want. I am not a fan of guess work when it comes to eyes and digits. I was not always this OCD about it, I consider myself lucky. Your parts your choice. Good luck, but know the facts not wives tales.

EDIT: I haven't used thousands of barrels yet. I have found 3 short chambers this year. This is a first for me, but I will keep checking them.

Posted: 12/8/2014 4:38:58 PM EDT

[#7]

Headspace is not set solely by installing the barrel extension.
The barrel extension is just one of the key elements that determine headspace.
All of the elements involved have tolerances.
Civilian barrel assemblies are not made under a legally binding government contract to a mil-spec and have to pass headspace checks with any bolt used.
The reality/fact is that some bolt/barrel combinations will not pass headspace checks.
Considering what I have seen for myself the defect rate in the civilian market is a lot more than 2%.
Granted that most are .002” or less out of spec and that ammo manufacturers hold their tolerances tight enough most people would never know that they had a potential problem.

Posted: 12/8/2014 8:01:07 PM EDT

[#8]

Nice rifle.

For a brand new rifle/upper it is best (safest) to check both “GO”, and “NO-GO”.

If you are feeling lucky, they buy just a Field gauge.

Some guys on this forum say these are good gauges – there is a set of three (go, no-go, field) for cheap:

http://www.mansonreamers.com/

I am not sure about the Manson gauges, but in almost all cases you have to disassemble the bolt to check headspace in an assembled Upper (barrel in the Upper Receiver).

There is one field gauge that you can use with an assembled bolt, but it is expensive:

http://www.billricca.com/collectors_corner.htm

Posted: 12/9/2014 11:18:35 AM EDT

[#9]

Rather than debate the point among those who agree to disagree, how about we ask every AR15 vendor if he headspaces the specific bolt to that barrel assembly? I betting that many won't answer, and those who declare they do are in the upper tier of precision makers.

When building my 6.8, I bought a matched headspaced barrel and bolt. It was cheaper from one source than chasing down separate parts. On this next build, nope. AR barrel vendors don't seem to make it a package deal very often.

If it was critical, every barrel sold would come with it's matching bolt.

They don't.

Thousands are assembled every year. The problem isn't as widespread as some make it out to be to justify the extra expense. That is because the AR was designed from the ground up with rocket science by aerospace engineers to eliminate the rocket science of assembling one. That made it cheaper as specially trained personnel are not needed in the assembly chain, and it eliminated expensive and time consuming steps to mate the barrel precisely to the receiver.

You just screw the barrel extension on, set the headspace, pin it, establish vertical from the feed ramps, drill the gas port, move to the next station.

I'm going to suggest that if someone is that confident in their ability check headspace they should consider doing that assembly themselves. The disadvantage is that separate barrel assembly parts and the labor to do it yourself is more expensive than a completed one shipped to the house.

Posted: 12/9/2014 11:51:31 AM EDT

[#10]

Quote History

Quoted:

Rather than debate the point among those who agree to disagree, how about we ask every AR15 vendor if he headspaces the specific bolt to that barrel assembly? I betting that many won't answer, and those who declare they do are in the upper tier of precision makers.
When building my 6.8, I bought a matched headspaced barrel and bolt. It was cheaper from one source than chasing down separate parts. On this next build, nope. AR barrel vendors don't seem to make it a package deal very often.
If it was critical, every barrel sold would come with it's matching bolt.
They don't.
Thousands are assembled every year. The problem isn't as widespread as some make it out to be to justify the extra expense. That is because the AR was designed from the ground up with rocket science by aerospace engineers to eliminate the rocket science of assembling one. That made it cheaper as specially trained personnel are not needed in the assembly chain, and it eliminated expensive and time consuming steps to mate the barrel precisely to the receiver.
You just screw the barrel extension on, set the headspace, pin it, establish vertical from the feed ramps, drill the gas port, move to the next station.
I'm going to suggest that if someone is that confident in their ability check headspace they should consider doing that assembly themselves. The disadvantage is that separate barrel assembly parts and the labor to do it yourself is more expensive than a completed one shipped to the house.

View Quote

Emails have been sent to many of the site sponsors. I will report back with any findings. I have done this because I am curious. I have seen on a few websites in passing when you buy a bolt or barrel, they warn you that you are responsible for checking the headspace. That would seem to me to indicate they think it is important. The question I asked is "Do you set headspace at barrel extension installation or do you also check the barrel bolt assembly with gauges"

EDIT: first response Del-Ton checks each complete upper that goes out with headspace gauges before it leaves.

second response DPMS---Yes we check the headspace and then test fire for function before they leave.

Posted: 12/9/2014 12:45:35 PM EDT

[#11]

Actually the AR was designed by an aircraft engineer at a time when the rocket scientists were creating massive explosions as often as not.

It is the responsibility of the builder of the weapon to put it together properly not the vendor who sold him the parts.
There are regular posts in the forums where people have had to send back uppers because things were not right.
Yes untrained inexperienced people put AR’s together all the time.
A person can tell by the number of help me posts where things did not work out so well.

Posted: 12/9/2014 2:03:14 PM EDT

[#12]

To OP- there is good advice here and some a little iffy. Do yourself a big favor. If you cant borrow the gages, then buy them. No matter what anyone tells you, USE them, no point arguing or even discussing the issue, or the what ifs. Just USE the damn gages, and better safe than sorry. Oh- and you dont have to disassemble the bolt. Just make sure everything is CLEAN, put the gage in the chamber and push the bolt home with your fingers. If it is good, with a GO gage, the bolt will close. If it is not good,with a NO GO gage, the bolt wont close. Very simple, just USE the friggin gages.

Posted: 12/9/2014 4:08:44 PM EDT

[#13]

A No-go gage fail is if the bolt closes.

Posted: 12/10/2014 10:47:48 AM EDT

[#14]

Third response...... Windham weaponry checks all barrel bolt combinations with headspace gauges.

Posted: 12/10/2014 10:55:06 AM EDT

[#15]

Quote History

Quoted:
Third response...... Windham weaponry checks all barrel bolt combinations with headspace gauges.

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Imagine that … industry professionals check headspace.
Neat piece of work you are doing.
Hopefully it will wake up some people.

Posted: 12/10/2014 3:32:29 PM EDT

[#16]

The two dimensions in the red boxes are what determines the headspace for an AR-15. If you subtract the bolt dimension 0.156" from the barrel dimension 1.6206", the headspace would equal 1.4646". This is the milspec for minimum headspace of a new barrel that has been high pressure tested (HPT).

The bolt dimension is from the bolt-face to the back edge of the bolt lugs, and the barrel dimension is from the 0.330" datum line of the chamber to the inside edge of the barrel extension lugs.

Posted: 12/10/2014 7:18:18 PM EDT

[#17]

Gunsmith at my local range checked headspace for $10. Cheaper than buying them and I'll probably not build another AR.

Posted: 12/10/2014 8:43:10 PM EDT

[#18]

You're more likely to fall and get hurt, as in seriously hurt, in your bathtub than have this be an issue. That's the percentages.

Truth is both sides are right here. IF the parts are new and made in spec, the headspace WILL be OK. There's nothing to check. That's what people mean when they say Stoner designed it a different way. The gotcha of course is that you are trusting the manufacturer built the parts to the proper tolerances. See percentages above. Sure it could happen, but it's very unlikely if your using quality made parts.

Where it really starts to matter is when you are putting together a build from used parts - a barrel thats already been used, an old bolt you picked up for $20 somewhere... then the wear on the two could be significant enough to matter. In that case, it would be much more prudent to check.

The cost isnt alot, if it makes you feel better, get the gauges and test it. I don't think anyone (and that's 99% of the people building on here) is being reckless when they don't check headspace on a new build. There's no certainties in this world.. and somewhere you just have to draw the line and live your life.

If it were as big of a deal as some here have said, then people wouldn't be skipping this step. Everyone on arfcom would be saying YOU HAVE TO DO THIS... so decide for yourself and then enjoy the new build.

Posted: 12/10/2014 10:44:35 PM EDT

[#19]

what is this "Air Gauged" thing I see on some vender's advertisements ??

Posted: 12/11/2014 12:05:03 AM EDT

[#20]

Quote History

Quoted:

You're more likely to fall and get hurt, as in seriously hurt, in your bathtub than have this be an issue. That's the percentages.

Truth is both sides are right here. IF the parts are new and made in spec, the headspace WILL be OK. There's nothing to check. That's what people mean when they say Stoner designed it a different way. The gotcha of course is that you are trusting the manufacturer built the parts to the proper tolerances. See percentages above. Sure it could happen, but it's very unlikely if your using quality made parts.

Where it really starts to matter is when you are putting together a build from used parts - a barrel thats already been used, an old bolt you picked up for $20 somewhere... then the wear on the two could be significant enough to matter. In that case, it would be much more prudent to check.

The cost isnt alot, if it makes you feel better, get the gauges and test it. I don't think anyone (and that's 99% of the people building on here) is being reckless when they don't check headspace on a new build. There's no certainties in this world.. and somewhere you just have to draw the line and live your life.

If it were as big of a deal as some here have said, then people wouldn't be skipping this step. Everyone on arfcom would be saying YOU HAVE TO DO THIS... so decide for yourself and then enjoy the new build.

View Quote

Or you can just use your out of spec parts as suggested above and if they do work being out of spec, you can watch them live a shortened life. That probably doesn't matter to guys shooting a hundred rounds a year. But its cool. Some people just don't care and you can't make them care. Some people do care. Apparently the three manufacturers that have responded to email care.

Also I heard 87% of all statistics are made up on the spot. So 99% of you aren't being reckless. And you are UNLIKELY to have ANY problems(like premature wear) if you use quality parts. If I find something out of spec, I will send it back just based on getting stuff that doesn't wear out prematurely. Please feel free to draw your own conclusions. And remember you are unlikely to have problems, and any gun you pick up is unlikely to be loaded??

Posted: 12/11/2014 1:23:53 AM EDT

[#21]

I have seen too many new barrel/bolts fail a headspace check to buy into the false “it does not need to be checked” theory.

Posted: 12/11/2014 2:14:16 AM EDT

[#22]

Life is like a box of chocolates.
I just like to check headspace. Makes me happy.

Posted: 12/11/2014 2:23:49 AM EDT

[#23]

Quote History

Quoted:
I have seen too many new barrel/bolts fail a headspace check to buy into the false “it does not need to be checked” theory.

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Well do tell us how many? Please!

Posted: 12/11/2014 3:56:13 AM EDT

[#24]

Quote History

Quoted:
what is this "Air Gauged" thing I see on some vender's advertisements ??

View Quote

Method used to measure the straightness and uniform diameter of the bore.

Posted: 12/11/2014 9:39:28 AM EDT

[#25]

I appreciate the effort to have makers respond to the headspacing question. Of course they check it.

DO THEY SHIP THE ACTUAL BOLT THEY CHECKED IT AGAINST? Most don't.

The answer we already have is that most barrels don't ship with the matched, headspaced bolt. Nada.

If it's important to have a matched set, buy them that way. Better done right before it even ships than after when it's too late. All you can do is return the parts - more expense and delay.

What I'm hearing is that some either could't find matching assemblies - very common - and found it was a nice way to enhance their rep by saying they check, then spreading their machismo on the boards as being a superior builder. Well, we went thru all this a few years back with the "squaring the upper" operation and discovered that is wasn't being done by a lot of the upper tier makers unless it was extra cost. They weren't doing it as a matter of practice on every build. They were guaranteeing the accuracy without it.

The question that should be asked of the makers is "Do you headspace a specific bolt to a barrel assembly and ship them together?" Not, "Do you check headspace?'

What they are doing is exactly what some are doing at home, slip in a nogo gauge and if it passes move it down the line. "Yes, of course we check the headspace."

They aren't saying they set the barrel extension with that specific bolt and then pin it, and keep them together, which is required on most other firearms. The AR is a different animal and traditional gun building procedures are exactly what Stoner was designing to eliminate. That is the rocket science in them.

You have to ask the right question to get the correct answer. The survey isn't asking the right question, it's asking one that they can answer with the least amount of information. We don't know they are headspacing the barrel assembly with that specific bolt then shipping them together.

Posted: 12/11/2014 11:11:06 AM EDT

[#26]

Yes, even a brand new complete rifle can have headspace issues. My recently purchased Bushmaster M4A3 Carbine fails with a Forster 1.4696 Field Gauge and a Clymer NATO no-go gauge, which oddly enough, also measures at 1.4696. With a new bolt from Aim surplus, it passes with both gauges. So there is at least one manufacturer who doesn't check the chamber with the bolt that is shipped.
.
I have a NATO 1.4736 Gauge on order, but meanwhile I have opened a ticket with BM. They are sending a mailing label and will schedule a home pick-up by UPS.

I am going to wait until my 1.4736 arrives and check it with that before I decide to send the rifle in. I already have a new PSA upper on order anyway.

Posted: 12/11/2014 2:20:35 PM EDT

[#27]

Quote History

Quoted:

I appreciate the effort to have makers respond to the headspacing question. Of course they check it.

DO THEY SHIP THE ACTUAL BOLT THEY CHECKED IT AGAINST? Most don't.

The answer we already have is that most barrels don't ship with the matched, headspaced bolt. Nada.

If it's important to have a matched set, buy them that way. Better done right before it even ships than after when it's too late. All you can do is return the parts - more expense and delay.

What I'm hearing is that some either could't find matching assemblies - very common - and found it was a nice way to enhance their rep by saying they check, then spreading their machismo on the boards as being a superior builder. Well, we went thru all this a few years back with the "squaring the upper" operation and discovered that is wasn't being done by a lot of the upper tier makers unless it was extra cost. They weren't doing it as a matter of practice on every build. They were guaranteeing the accuracy without it.

The question that should be asked of the makers is "Do you headspace a specific bolt to a barrel assembly and ship them together?" Not, "Do you check headspace?'

What they are doing is exactly what some are doing at home, slip in a nogo gauge and if it passes move it down the line. "Yes, of course we check the headspace."

They aren't saying they set the barrel extension with that specific bolt and then pin it, and keep them together, which is required on most other firearms. The AR is a different animal and traditional gun building procedures are exactly what Stoner was designing to eliminate. That is the rocket science in them.

You have to ask the right question to get the correct answer. The survey isn't asking the right question, it's asking one that they can answer with the least amount of information. We don't know they are headspacing the barrel assembly with that specific bolt then shipping them together.

View Quote

All I can say is Oliver Stone conspiracy theory. Only one manufacturer so far has left the which bolt to which barrel vagueness in their email. But hey, whatever you want to believe. Maybe you could take some time to write some emails???? WOW unbelievable

Posted: 12/11/2014 3:58:41 PM EDT

[#28]

Quote History

Quoted:
All I can say is Oliver Stone conspiracy theory. Only one manufacturer so far has left the which bolt to which barrel vagueness in their email. But hey, whatever you want to believe. Maybe you could take some time to write some emails???? WOW unbelievable

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
I appreciate the effort to have makers respond to the headspacing question. Of course they check it.

DO THEY SHIP THE ACTUAL BOLT THEY CHECKED IT AGAINST? Most don't.

The answer we already have is that most barrels don't ship with the matched, headspaced bolt. Nada.

If it's important to have a matched set, buy them that way. Better done right before it even ships than after when it's too late. All you can do is return the parts - more expense and delay.

What I'm hearing is that some either could't find matching assemblies - very common - and found it was a nice way to enhance their rep by saying they check, then spreading their machismo on the boards as being a superior builder. Well, we went thru all this a few years back with the "squaring the upper" operation and discovered that is wasn't being done by a lot of the upper tier makers unless it was extra cost. They weren't doing it as a matter of practice on every build. They were guaranteeing the accuracy without it.

The question that should be asked of the makers is "Do you headspace a specific bolt to a barrel assembly and ship them together?" Not, "Do you check headspace?'

What they are doing is exactly what some are doing at home, slip in a nogo gauge and if it passes move it down the line. "Yes, of course we check the headspace."

They aren't saying they set the barrel extension with that specific bolt and then pin it, and keep them together, which is required on most other firearms. The AR is a different animal and traditional gun building procedures are exactly what Stoner was designing to eliminate. That is the rocket science in them.

You have to ask the right question to get the correct answer. The survey isn't asking the right question, it's asking one that they can answer with the least amount of information. We don't know they are headspacing the barrel assembly with that specific bolt then shipping them together.

All I can say is Oliver Stone conspiracy theory. Only one manufacturer so far has left the which bolt to which barrel vagueness in their email. But hey, whatever you want to believe. Maybe you could take some time to write some emails???? WOW unbelievable

I followed this thread carefully. Which part of what the man said is "unbelievable"? I don't think you are following what the guy is getting at. Missing his point. thats how it seems.

Posted: 12/11/2014 6:14:27 PM EDT

[#29]

Fourth response....

Headspace is checked on each upper and rifle order.
THANK YOU,
REPAIR / TECH SUPPORT

xxx@ROCKRIVERARMS.COM

the exact email cut and pasted i sent to RRA

Message:

I have a question about headspace. When you send out a complete upper or rifle do you check each barrel and bolt with a gauge for headspace? Or, as I have been told by people not affiliated with RRA, do you set the headspace with installation of barrel extension? thanks

EDIT to pyroclayman: The unbelievable part is he originally stated they set the head space with the barrel extension and then forget about it and don't check with a gauge. Now(again with no proof of his statement) its not the same bolt. Next it will be the boogie man swaps the barrels in the mail or anything you can imagine. Even IF they used different bolts, the bolts used are theirs, built to their specs within their tolerances to match their barrel specs. Not that I agree with that or that thinking. But at least if something like this occurred its a much tighter quality control that billy bobs barrels mated to bobby sue's bolts, one made on the left coast and one made on the right coast, one made to spec sheet "A" and the other made to spec sheet "87"?? There are many variables I get it. He changed course to a back up argument when proven wrong.

I will report more replies as they come in, done with the "you are still wrong, the world is rosy without checking" debate.

Posted: 12/11/2014 11:31:09 PM EDT

[#30]

What is unbelievable to me is that someone would argue that a headspace check is unnecessary which totally ignores the fact that some bolt/barrel combinations fail headspace checks.
I have run across four or five in the last few years and for my money catching one paid for the gages.
Stoner was a smart guy, but he designed a combat rifle and these days the platform has been stretched to include everything from pistols to precision match rifles.

Posted: 12/12/2014 7:14:39 AM EDT

[#31]

Who has the best price on "go" & "no go" gauges?

Posted: 12/12/2014 9:03:52 AM EDT

[#32]

I believe www.mansonreamers.com offers a go, no go, and field for $60. They used to anyway. That is a steal. I have Manson gauges.

Posted: 12/13/2014 12:27:40 AM EDT

[#33]

Fifth response.......

Lug1, yes we check the head spacing and test fire all rifles and uppers before they are sent out.

Thank you

exact email cut and pasted

Message:

I am wondering if Stag checks each complete rifle or upper sent out for headspace with a gauge? I have been told by some, not affiliated with your company, that headspace is set with the barrel extension and never checked with the bolt sent out. So I wonder what your actual practice is? Do you check barrel and bolt with a gauge before leaving the factory?

Posted: 12/17/2014 3:02:59 PM EDT

[#34]

So I found a maximum headspace gauge on ebay for $32 shipped(surprisingly hard to find in stock at most places). And I heard someone say (another arfcommer, in some other thread) that all you need is the max gauge and a 5.56 snap cap. Should close on the snap cap and not on the max. That sound right?

Posted: 12/17/2014 5:00:07 PM EDT

[#35]

Not just no, but hell no!
The most common problem with new barrels is failing the Go gage not the No-go gage.
Also if a new barrel fails the No-go gage you can send it back as its service life may be compromised.
There is no substitute for a proper gage.
Snap caps, live ammo, etc. are manufactured to a different tolerance range and accordingly are not even close.
The max chamber gages are for weapons that were properly checked when new.

Posted: 12/17/2014 5:14:34 PM EDT

[#36]

Quote History

Quoted:
Not just no, but hell no!
The most common problem with new barrels is failing the Go gage not the No-go gage.
Also if a new barrel fails the No-go gage you can send it back as its service life may be compromised.
There is no substitute for a proper gage.
Snap caps, live ammo, etc. are manufactured to a different tolerance range and accordingly are not even close.
The max chamber gages are for weapons that were properly checked when new.

View Quote

Good advice.

So, if a person was on a budget and could only buy one gauge to start off with, the max gauge is the one to start with. That sound right?

Posted: 12/17/2014 6:27:13 PM EDT

[#37]

Quote History

Quoted:
What is unbelievable to me is that someone would argue that a headspace check is unnecessary which totally ignores the fact that some bolt/barrel combinations fail headspace checks.
I have run across four or five in the last few years and for my money catching one paid for the gages.
Stoner was a smart guy, but he designed a combat rifle and these days the platform has been stretched to include everything from pistols to precision match rifles.

View Quote

I'm just guessing here.... but perhaps because the risk of using an AR that fails headspace is very, very minimal.

If the headspace is short, you will get fail to chamber and fail to lock malfunctions. The only risk would be if you were using ammunition near the maximum pressure allowed, you might see signs of overpressure, such as brass flow, flat or popped primers, etc. You might notice it is hard to extract a chambered but unfired round.

If the headspace is long, you likely wont see any issues whatsoever and would likely not even know there was an issue. It will simply allow the brass to stretch a tad bit more, resulting in lower pressures. Popped primers could occur here too, since the case head could potentially be farther from the bolt face, and case head separations could potentially increase due to this condition, however also very rare. I always use the headspace of the M249 SAW as an example. Compare that to the M16 chamber, both using the same exact ammunition.

Posted: 12/17/2014 6:40:50 PM EDT

[#38]

3 short chambers in 2014, 2 of which chambered a round(if those barrels had been used increased wear on part due to higher pressures). Long headspace? Well I like how people constantly say chances of anything happening are minimal. I get that. Now you get a bubba who is confident in his reloading skills and overuses brass. And while your long headspace may do nothing in new military brass, what about the what if's in this scenario. I know guys who do this. They seem to live on the edge to me, but none of them have had anything bad happen. Seen a couple case head separations and all is well(enough). I still say it is too easy to check and know.

You can call manson reamers and buy the gauges directly from them. There are some other fine manufacturers of the gauges. I would buy nothing gun related through ebay. For that matter I buy nothing through ebay.

Posted: 12/17/2014 7:27:11 PM EDT

[#39]

Quote History

Quoted:
3 short chambers in 2014, 2 of which chambered a round(if those barrels had been used increased wear on part due to higher pressures). Long headspace? Well I like how people constantly say chances of anything happening are minimal. I get that. Now you get a bubba who is confident in his reloading skills and overuses brass. And while your long headspace may do nothing in new military brass, what about the what if's in this scenario. I know guys who do this. They seem to live on the edge to me, but none of them have had anything bad happen. Seen a couple case head separations and all is well(enough). I still say it is too easy to check and know.

You can call manson reamers and buy the gauges directly from them. There are some other fine manufacturers of the gauges. I would buy nothing gun related through ebay. For that matter I buy nothing through ebay.

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I've been looking around the Manson website but I'm not seeing any 5.56 gauges. I don't know if I'm just not seeing them or if the're not there?

Are they actually military 5.56 gauges or .223 spec? Do you have to disassemble the bolt when using them?

Posted: 12/17/2014 7:34:56 PM EDT

[#40]

The gages I found on ebay are from forster products.

They are on their website as well. Although they don't show in stock or not in stock. They seem like a good company.

Edit: to say these are 5.56 NATO as well.

Posted: 12/17/2014 9:34:23 PM EDT

[#41]

I didn't check headspace on my mutt builds (bought a complete upper for the barrel) that I swapped the barrels on but I did keep the bolts with the barrels as I swapped the carriers two. As my rifles evolve the bolt and barrel always stay together.

Posted: 12/18/2014 12:41:56 AM EDT

[#42]

Quote History

Quoted:
I've been looking around the Manson website but I'm not seeing any 5.56 gauges. I don't know if I'm just not seeing them or if the're not there?

Are they actually military 5.56 gauges or .223 spec? Do you have to disassemble the bolt when using them?

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Quote History

Quoted:

Quoted:

3 short chambers in 2014, 2 of which chambered a round(if those barrels had been used increased wear on part due to higher pressures). Long headspace? Well I like how people constantly say chances of anything happening are minimal. I get that. Now you get a bubba who is confident in his reloading skills and overuses brass. And while your long headspace may do nothing in new military brass, what about the what if's in this scenario. I know guys who do this. They seem to live on the edge to me, but none of them have had anything bad happen. Seen a couple case head separations and all is well(enough). I still say it is too easy to check and know.

You can call manson reamers and buy the gauges directly from them. There are some other fine manufacturers of the gauges. I would buy nothing gun related through ebay. For that matter I buy nothing through ebay.

I've been looking around the Manson website but I'm not seeing any 5.56 gauges. I don't know if I'm just not seeing them or if the're not there?

Are they actually military 5.56 gauges or .223 spec? Do you have to disassemble the bolt when using them?

Just call Manson if you are interested in them. All my gauges are Manson, they do have a slice on the head that the ejector fits in. I generally remove the extractor though.

Posted: 12/18/2014 10:06:15 AM EDT

[#43]

Quote History

Quoted:

I'm just guessing here.... but perhaps because the risk of using an AR that fails headspace is very, very minimal.

If the headspace is short, you will get fail to chamber and fail to lock malfunctions. The only risk would be if you were using ammunition near the maximum pressure allowed, you might see signs of overpressure, such as brass flow, flat or popped primers, etc. You might notice it is hard to extract a chambered but unfired round.

If the headspace is long, you likely wont see any issues whatsoever and would likely not even know there was an issue. It will simply allow the brass to stretch a tad bit more, resulting in lower pressures. Popped primers could occur here too, since the case head could potentially be farther from the bolt face, and case head separations could potentially increase due to this condition, however also very rare. I always use the headspace of the M249 SAW as an example. Compare that to the M16 chamber, both using the same exact ammunition.

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Quoted:

Quoted:
What is unbelievable to me is that someone would argue that a headspace check is unnecessary which totally ignores the fact that some bolt/barrel combinations fail headspace checks.
I have run across four or five in the last few years and for my money catching one paid for the gages.
Stoner was a smart guy, but he designed a combat rifle and these days the platform has been stretched to include everything from pistols to precision match rifles.

I'm just guessing here.... but perhaps because the risk of using an AR that fails headspace is very, very minimal.

If the headspace is short, you will get fail to chamber and fail to lock malfunctions. The only risk would be if you were using ammunition near the maximum pressure allowed, you might see signs of overpressure, such as brass flow, flat or popped primers, etc. You might notice it is hard to extract a chambered but unfired round.

If the headspace is long, you likely wont see any issues whatsoever and would likely not even know there was an issue. It will simply allow the brass to stretch a tad bit more, resulting in lower pressures. Popped primers could occur here too, since the case head could potentially be farther from the bolt face, and case head separations could potentially increase due to this condition, however also very rare. I always use the headspace of the M249 SAW as an example. Compare that to the M16 chamber, both using the same exact ammunition.

I agree the risk seems to be minimal.
For one thing the ammo manufacturers seem to keep their ammo toward the low end of the tolerance range.
This would mean that even with a chamber a couple of thousandths short there would not be a chambering problem.
One of the things I keep going back to is even with that lot of overpressure ammo that got out a while back only some of the weapons it was used in went KB.
I also agree that new good ammo is not likely to have a problem with excessive headspace.
However like Lug1 I think reloaded cases are a problem with weapons that have excessive headspace.
I would also note that since I was an armorer the military seems much more concerned about excessive headspace in rifles.
Even minimal risk implies some people draw the short straw.
The ironic aspect is that the situation is avoidable with a simple check.

Posted: 12/18/2014 10:42:55 PM EDT

[#44]

Quote History

Quoted:
However like Lug1 I think reloaded cases are a problem with weapons that have excessive headspace.
I would also note that since I was an armorer the military seems much more concerned about excessive headspace in rifles.

View Quote

What's your take on this:

M16 chamber:
Military GO 1.4646" - 1.4648"
Military NOGO 1.4704" - 1.4706"
Military FIELD 1.4728" - 1.4730"
Colt's FIELD II 1.4736"

M249 SAW
M249 SAW GO 1.4940" - 1.4947"
M249 SAW NOGO 1.4982" - 1.4980"
M249 SAW FIELD 1.50216" - 1.50196"

The failure to pass a Colt Field II gauge would cause the military to replace a barrel for sure, which is 1.4736"

However, if that is such a safety concern, why is the MINIMUM chamber spec for the M249 1.4940", which is a MASSIVE .022" larger?

Posted: 12/18/2014 11:26:57 PM EDT

[#45]

Quote History

Quoted:
What's your take on this:

M16 chamber:

Military GO 1.4646" - 1.4648"

Military NOGO 1.4704" - 1.4706"

Military FIELD 1.4728" - 1.4730"

Colt's FIELD II 1.4736"

M249 SAW

M249 SAW GO 1.4940" - 1.4947"

M249 SAW NOGO 1.4982" - 1.4980"

M249 SAW FIELD 1.50216" - 1.50196"

The failure to pass a Colt Field II gauge would cause the military to replace a barrel for sure, which is 1.4736"

However, if that is such a safety concern, why is the MINIMUM chamber spec for the M249 1.4940", which is a MASSIVE .022" larger?

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Quote History

Quoted:

Quoted:

However like Lug1 I think reloaded cases are a problem with weapons that have excessive headspace.

I would also note that since I was an armorer the military seems much more concerned about excessive headspace in rifles.

What's your take on this:

M16 chamber:

Military GO 1.4646" - 1.4648"

Military NOGO 1.4704" - 1.4706"

Military FIELD 1.4728" - 1.4730"

Colt's FIELD II 1.4736"

M249 SAW

M249 SAW GO 1.4940" - 1.4947"

M249 SAW NOGO 1.4982" - 1.4980"

M249 SAW FIELD 1.50216" - 1.50196"

The failure to pass a Colt Field II gauge would cause the military to replace a barrel for sure, which is 1.4736"

However, if that is such a safety concern, why is the MINIMUM chamber spec for the M249 1.4940", which is a MASSIVE .022" larger?

The SAW has a double angle, the M16 doesn't causing a longer distance from the datum? The heavier projectiles were causing pressure spikes? This is what I am reading. I do not know this to be hard and fast.

There is still a potential issue in civilian market with reloaders and brass, the government market does not contend with.

Posted: 12/19/2014 12:27:15 AM EDT

[#46]

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Quoted:
There is still a potential issue in civilian market with reloaders and brass, the government market does not contend with.

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Are you an experienced long time reloader? Or are you talking in theories based on what you read somewhere?

Reloaders often:

1. Only bump the shoulder back when reloading ammo for a specific rifle, minimizing this impact to the first firing only.
2. Reload brass until they start to get an occasional case head separation, which is fairly common and not a big deal. I have had several myself. Granted - we don't want to advocate case failure, but work hardening, split necks, and case head seps are part of the process. You tend to learn how many reloads you can get out of a batch or brand of brass based on these outcomes.

Posted: 12/19/2014 10:04:17 AM EDT

[#47]

Quote History

Quoted:

What's your take on this:

M16 chamber:
Military GO 1.4646" - 1.4648"
Military NOGO 1.4704" - 1.4706"
Military FIELD 1.4728" - 1.4730"
Colt's FIELD II 1.4736"

M249 SAW
M249 SAW GO 1.4940" - 1.4947"
M249 SAW NOGO 1.4982" - 1.4980"
M249 SAW FIELD 1.50216" - 1.50196"

The failure to pass a Colt Field II gauge would cause the military to replace a barrel for sure, which is 1.4736"

However, if that is such a safety concern, why is the MINIMUM chamber spec for the M249 1.4940", which is a MASSIVE .022" larger?

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
However like Lug1 I think reloaded cases are a problem with weapons that have excessive headspace.
I would also note that since I was an armorer the military seems much more concerned about excessive headspace in rifles.

What's your take on this:

M16 chamber:
Military GO 1.4646" - 1.4648"
Military NOGO 1.4704" - 1.4706"
Military FIELD 1.4728" - 1.4730"
Colt's FIELD II 1.4736"

M249 SAW
M249 SAW GO 1.4940" - 1.4947"
M249 SAW NOGO 1.4982" - 1.4980"
M249 SAW FIELD 1.50216" - 1.50196"

The failure to pass a Colt Field II gauge would cause the military to replace a barrel for sure, which is 1.4736"

However, if that is such a safety concern, why is the MINIMUM chamber spec for the M249 1.4940", which is a MASSIVE .022" larger?

I am aware of the difference and on the surface it is a huge discrepancy.
My current take is for whatever reason an AR will start having problems before the headspace gets to M249 Go specs, but even that is based on some anecdotal stories.
Whatever the truth may turn out to be in the meantime I am going to stick with what SAAMI, Colt, and the military state is the safe limit on general principle.

Posted: 12/19/2014 11:01:46 AM EDT

[#48]

I agree with the consensus.

Most random combinations of AR barrels and bolts will work just fine, and will pass headspacing checks.

But there is a small chance you may get a combination that won't pass, and either have jamming problems (headspace too short) or case head separations (headspace too long).

Since you can get a set of GO and NO-GO gauges for around $50, if you build ARs regularly, there's really no excuse for not getting a set and checking your work before firing. If you don't, it's a good idea to either borrow a gauge set, or have someone check headspace for you. The risk is low, but the consequences can be catastrophic.

Posted: 12/19/2014 12:55:18 PM EDT

[#49]

If the head space is wrong you can't even fix it yourself anyway. So take that into consideration in your head space quest!

Many many decent ranges will check headspace go-no-go for free since it is a safety issue.

Posted: 12/19/2014 1:31:26 PM EDT

[#50]

Quote History

Quoted:

If the head space is wrong you can't even fix it yourself anyway. So take that into consideration in your head space quest!

Many many decent ranges will check headspace go-no-go for free since it is a safety issue.

View Quote

Other than change the bolt or ream a stainless or unlined chamber, OR SEND BACK THE PARTS. And this is my overall point. If I buy a barrel that will not pass headspace check with the intended bolt or any of a few spares I keep, I will send it back. This is not a problem for me. As I have stated it has only happened 3 times. It really is not something that happens everyday. My issue is people like to state headspace means nothing or doesn't need to be checked, I believe are wrong. I have never been part of a headspace KB. Why is that? Lucky or I check or I don't have enough volume to have gotten to that point of bad parts, or todays parts are built so well they won't KB.

I don't care what the answer is, I will send back out of spec parts because I want my money's worth. Nobody making anybody do anything, but checking it is the best idea. If you don't agree cool, I hope your parts never KB.

Faralak, I am not an experienced reloader. I am learning from one particular friend I have known for 30 years+. He has been reloading for at least that long. He is thorough in his procedures and often shows me his references in books when he is teaching me something. There is a circle of guys there. And a couple that I am choosing not to learn from play very fast and loose. I am certain they are not the only 2 guys in this country or the world that reload this way. This is my point. I get that there is book learning and there is a reality. To my knowledge the guy I am relying on has had 1 case head separation ever or at least in the last several years, and that is reality. I know things can happen on a regular basis that are not catastrophic. But there have been a few instances of some bad things.

And please respond back to my reasoning on the M249 having the double angle causing the long headspace. It is something I read and you seem to have some knowledge on the issue.

[ARCHIVED THREAD] - Headspacing on built rifle? (noob) (Page 1 of 2)

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