So I'm still waiting for my lower via the group buy. But my upper is built. The bcg came assembled. I installed barrel that came with kit and pinned the gas tube. When the lower gets built I hope to shoot this thing. So do I really need to check the headspace ? I also don't wanna be picking up my hand or face from the ground ya know what I mean?
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Ar15 headspace ?
- Thread starter HiVolt
- Start date
warwickben
bubba Kalashnikov
I'll shoot it for you 
warwickben
bubba Kalashnikov
I've heard people say if there Name brand don't worry unless it dpms .
Then I heard you should allways .
Then I heard you should allways .
This is a good question! I recently finished my first build. I did the lower but I bought a built upper iit was from AR-15 .com classifieds. It was a hodgepodge upper of mixed parts and assembled by the gentleman I ordered it from. I bought a field gauge from midway or brownells...can't remember. The problem is that I don't really know how to use the gauge. So I have not shot the gun as of yet. So I will be keeping an eye on this thread as well
Most of the time there isn't an issue...but there's always a chance. If you plan on building more rifles, it's worth investing in a set of Go/No Go gauges. If you're just doing the one, then maybe you can get someone to help you out. You will need to remove the ejector pin and spring as well as the extractor from the bolt you plan on using.
A field gauge is better than not checking it at all, but a go/no go would be better as a FG is typically used for well worn rifles.
As previously mentioned, remove the ejector pin and spring from the bolt. Separate the upper from the lower. Flip the upper upside down and insert the gauge. Push the bolt forward as far in as it will go. With the field gauge, as with the no go gauge, the bolt should not fully engage, meaning it should be protruding slightly from the upper receiver. That's pretty much it.
Mr. Brownstone
NES Member
OP, yes check it. Where are you located, if you are close, I can help you, if you are close to Worcester give "not tom" a shout, I have seen him offer to help people before on head space issues.
JayMass. The way you use the field gauge is;
detach lower from upper (the reason you detach them is that if you are headspaced properly the bolt will not close on a NO-Go or Field Gauge. You don't want the bolt carrier to come slamming forward on the gauge.)
load gauge carefully, into the chamber.
insert bolt carrier group slowly and close on the gauge.
BCG should ALMOST close but not quite.
You have now insured that you do not have excessive head space.
So a No Go gauge and a field gauge are similar because they "pass" the test if the bolt will not close. The NOGO is a bit more conservative as it will fail a chamber that a field gauge will pass. The field gauge was made for just that, the field. If a weapon needed to be checked in the field, the gauge would tell them if it was safe to keep using. The No Go is what you want to use if you won't be checking often as wear on the bolt will increase head space.
A GO gauge "passes" when the bolt closes. My understanding of it is that you do not need the "go" gauge because the bolt won't close on a round if there is not enough head-space.
JayMass. The way you use the field gauge is;
detach lower from upper (the reason you detach them is that if you are headspaced properly the bolt will not close on a NO-Go or Field Gauge. You don't want the bolt carrier to come slamming forward on the gauge.)
load gauge carefully, into the chamber.
insert bolt carrier group slowly and close on the gauge.
BCG should ALMOST close but not quite.
You have now insured that you do not have excessive head space.
So a No Go gauge and a field gauge are similar because they "pass" the test if the bolt will not close. The NOGO is a bit more conservative as it will fail a chamber that a field gauge will pass. The field gauge was made for just that, the field. If a weapon needed to be checked in the field, the gauge would tell them if it was safe to keep using. The No Go is what you want to use if you won't be checking often as wear on the bolt will increase head space.
A GO gauge "passes" when the bolt closes. My understanding of it is that you do not need the "go" gauge because the bolt won't close on a round if there is not enough head-space.
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ntomsw
Banned
Yes, check it. It takes 30 seconds to check, so you don't blow your face off. If you are anywhere local to Worcester, I will check it for you.
All you need is go/no-go gauges. I won't use a field gauge. Field gauge is pretty much right at the line of being safe to shoot.
Get a set of Forster go/no go, or PM me and I will check it for you.
All you need is go/no-go gauges. I won't use a field gauge. Field gauge is pretty much right at the line of being safe to shoot.
Get a set of Forster go/no go, or PM me and I will check it for you.
Here's my take, I just finished my first build.
Actually been complete for a week. Tomorrow it is hitting the range, today I will put the bolt in it and I WILL check the head space.
It cost me $50 for the go/no go gauges, it's worth my piece of mind.
Heck, if anyone close by to me wants to check and doesn't have the gauges, let me know
Actually been complete for a week. Tomorrow it is hitting the range, today I will put the bolt in it and I WILL check the head space.
It cost me $50 for the go/no go gauges, it's worth my piece of mind.
Heck, if anyone close by to me wants to check and doesn't have the gauges, let me know
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If you're in the Groton/Shirley area, I have a set of gages and I can check it for you.
Brownell's and UltimateReloader.com have pretty comprehensive video library specifically about building AR15s. Brownell's also has videos on a lot of individual products - including the use of head space gauges. Here is the video on using the head space gauge (you might have to click on a few links to find the correct video.
ETA: Change the to a more apropriate AR15 related video on head space checking.
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I'm in the Boston area, I have 5.56 gauges. Let me know if you need help.
Mine cost $85 for the set but I rather check than blowing my face off.
From what I hear there's a difference in 5.56 and .223 gauges **shrug** But just letting you know I have a 5.56 chamber so that's what I bought for gauges.
Mine cost $85 for the set but I rather check than blowing my face off.
From what I hear there's a difference in 5.56 and .223 gauges **shrug** But just letting you know I have a 5.56 chamber so that's what I bought for gauges.
DemonChronicles
NES Member
Eddie,
I am staying in Shirley for the foreseeable future and would like to take you up on that offer, just for piece of mind if not anything else.
PM me if you're still up for this. Thanks.
Curious on this one.
30 seconds? I am wondering if there is a different way to check?
I pulled off the upper, removed the BCG, pulled out the ejector, tested with go/no go, replaced ejector, replaced BCG
It only took a few minutes but wan't 30 seconds so is there a different way to do that I am missing?
30 seconds? I am wondering if there is a different way to check?
I pulled off the upper, removed the BCG, pulled out the ejector, tested with go/no go, replaced ejector, replaced BCG
It only took a few minutes but wan't 30 seconds so is there a different way to do that I am missing?
ntomsw
Banned
I use Forster gauges, and with them, you don't have to take apart your BCG. So yes, about 30 seconds to check it. If that.
Hmm, those are the gauges I have.
Next build I'll save myself a few minutes then
Thanks
Next build I'll save myself a few minutes then
Thanks
That depends on the clambering. A 5.56 chamber WILL accept a .223 no go headspace gauge. It will be a tight fit but the bolt will close. It should not close on a field gauge.
Te tools don't cost much, and the safety factor would seem a worth while investment. There are plenty of videos on how to headspace an AR on you tube. If the upper wasn't purchased as a complete unit with BCG from a good manufacturer then I would do it.
I've got Forster 223 Gauges as well. You don't need to remove the ejector or extractor to use them properly?
I found that curious also. I dug out the instructions for my gauges and it says "for best result remove the extractor. It doesn't say you HAVE to remove it, so I'm going to give that a try next time.
ntomsw
Banned
You DO NOT have to take the BCG a part with the Forster gauges. Member 'jasons' here showed me about it first hand with his gauges, and then I bought my own, and they do the same thing.
With the rifle assembled, throw in the go gauge into the chamber. Slowly release the charging handle and close it on the gauge. Press gently on the forward assist to see if the BCG will close all the way. It should close on the go gauge.
Do the exact same thing with the no go gauge. It should NOT close on the no go gauge. If it does, you have problems, and the rifle should not be fired.
These are my gauges. I have a set of .223 & 5.56
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I have a lane at Manchester Firing Line for 6, could you check mine? I really would like to start shooting this thing, and completely forgot about checking the headspace.....
Hardwired
NES Member
I just ordered a "Down & Dirty" .223 Rem headspace gauge set from Manson Reamers. The Down & Dirty doesn't have the rim on the bottom to clear the ejector and the sides aren't polished which saves some cost. Dave Manson told me no need to remove the ejector with these. The D&D set comes with the Go, NoGo, and Field for $60 + shipping/insurance (the shipping charge was higher than I expected but I guess I should asked on the shipping rate options).
Now I'm wondering if I shouldn't have gotten 5.56 gauges as my barrels are chambered for 5.56.
Will the bolt really close on .223 NoGo for a 5.56/.223 barrel??
Now I'm wondering if I shouldn't have gotten 5.56 gauges as my barrels are chambered for 5.56.
Will the bolt really close on .223 NoGo for a 5.56/.223 barrel??
If you look at the chamber demensions the head space is off the shoulder is very close for all the 223 family Nato, wylde, clef and from manufacture to manufacture. What difffers more so is the free bore and angle of the throat. 5.56 Nato is chambered or constructed to take more preasure. A 223 head space guage should be fine for a 5.56 chamber for safety.....best to ask the manufacture though.
Hardwired
NES Member
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So much incorrect here. I'll start at the beginning.
Don't bother with a field gauge. You're not buying a 100 year old milsurp.
The go gauge and the no-go gauge are two separate gauges. You need both.
No need to remove the "ejector pin and spring" from the bolt. (Also no need to remove the ejector....)
Bolt should not close on the no-go gauge, but that's not "pretty much it." You also need to make sure that it WILL CLOSE on the go gauge. If you just test one you've only done half the job.
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Just get the .223 gauges. The chamber dimensions are basically the same (except for the leade but that won't affect headspace.) The specs for 5.56 allow for a little more (like .002" more if I remember correctly) slop in maximum headspace, but generally you don't want slop - it's bad for accuracy and tougher on brass.
EDIT:
This explains it better than I can:
http://www.ar15barrels.com/data/headspace.pdf
In summary, the difference between the .223 and 5.56 nogo gauge is about .0036". (When they say "civilian" they mean .223, when the say "military" they mean 5.56.)
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I've built a handful of rifles for myself and with friends and never bothered to check. If you are using quality name brand parts (barrel, bcg) and you trust the factory qcd them so they are in spec you should not have an issue. Its not something the end user can **** up on an AR.
Mike
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Mike
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