Bolt closing on field gauge

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I finished my first AR build last weekend and just got a 5.56 field gauge (1.4736") in yesterday to check the headspace.
http://www.brownells.com/gunsmith-t...uges/5-56mm-223-headspace-gauge-prod6646.aspx

I took the ejector and extractor out of the bolt, put everything back together, and put the gauge in the chamber. The bolt stops moving easily long before it is closed, but if I keep pushing with my thumb I can get it to close completely. I have to push hard, but it I do just with my thumb it will close.

I then checked the gauge with my fairly new M&P 15. I didn't take the time to strip the bolt and just tested it with the ejector and extractor still in. Again, I had to push hard, but it would close on the gauge. I had to push even harder, but still just with my thumb. I figure on that one I am fighting the ejector so I would have to really push on it anyway.

So how hard do people usually push to check the headspace? I looked around for a long time and all I can find is to make sure you push it carefully. I have no idea what that means. I also saw on here that some people are testing with the ejector still in so they must really be pushing to overcome that. Did I just get a bad gauge, or am I pushing too hard?
 
For shits and giggles I read the instructions and per the instructions they make it out like colt has a special chamber? The measurement on the guage is the same Max as 223 rem found in the saami specs.
As per instructions the bolt should not close so if you can close it. Well its out of spec.... now is it the chamber,bolt, guage?
Why don't we start with what you built. Parts manufactures ectect? New used?

http://www.ar15.com/archive/topic.html?b=3&f=66&t=417420 found this may help
 
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My build is all new spikes bcg and upper, windham weaponry barrel. But again, I also tried the gauge in my s&w m&p15 (approximately 500 rounds through) and it closed there too. I read up on the subject a lot and the consensus is headspace issues with quality ARs are rare to nonexistent. So maybe I struck the lotto in a bad way with 2 out of spec ARs. It seems more likely that I am doing something wrong or the gauge is bad.


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Are you positive its not a "go " gauge?
Eta

Noticed you had a.223 gauge and a 5.56 barrel.

Similarly, the 5.56 NATO caliber requires a slightly longer headspace than the commercial .223 caliber, which are commonly thought to be identical. For that reason, Forster Products is also offering 5.56 NATO Headspace Gages. For any gunsmith or armorer working with military firearms in these two calibers, these NATO Headspace Gages can make a huge difference in both performance and safety.[\quote]
Click to expand...
 
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Mr. Brownstone said:
Are you positive its not a "go " gauge?
Click to expand...

Well, no, but I don't think it is. The field gauge specs are printed on the gauge but it is possible they screwed up. Probably would be what I get for ordering the cheapest one.

It is stamped as .223, but listed as 5.56 at brownells. I looked up what the specs should be and it seems like 1.4736" is the largest gauge made for either caliber. That is the length of the NATO field gauge.


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I've never seen one that bad that didn't have like 100,000 rounds on it. Something's wrong. (I don't even use a field gauge. If the bolt closes on a no-go something's wrong. If it closes on a field gauge something's REALLY wrong. Like don't shoot it wrong.)

If you can get to Malden sometime you can try my gauges.

Edit: 1.4736" is the same as Colt's "Field II" gauge, which is even longer than a normal field gauge. The military field gauges aren't even that long. Send that thing back.

http://www.ar15barrels.com/data/headspace.pdf
 
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Was hoping Jasons might chime in. Now that I am home from work and can actually type.

Same offer for Georgetown, although I think he may be closer.

Check in with Canislupy. He is in the Worcester area and has offered to help out with HS in this thread.
http://www.northeastshooters.com/vb...No-Go-Gauges?p=3669270&viewfull=1#post3669270

It seems weird to me that this would happen on two completely different rifles, one of which being a factory rifle that has a low round count.

Couple more questions. When you tested on the M&P, did you use the bolt that has been with the rifle the whole time, or the one from the build?

Are you sure the bolt is closing all the way?

Aside from that, I wouldn't shoot it until it was checked out. Field gauge is designed to be a last ditch test in the field. If it passes, yeah you can shoot it, but it is time to replace bolt or barrel asap.
 
It can be a pain but how about removing the barrel on your build and just test head space with bolt?
I to am guessing a bad tool. Maybe a local reloader has a case guage. The head space guage should show its face, maybe?
Also compare the shoulder angle with some ammo? Do you have a way to try and measure the gauge?

Jasons: that link was pretty cool. Looking at the saw specs I started laughing.. no wonder reloaders have so much fun when they get once fired brass from a saw!
 
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Thanks everybody, I appreciate the help. When I tested the m&p it was with its original bolt. There are a couple of people in that other thread that aren't too far from me. I will try to see if any of them can let me use their gauges. I also might contact brownells and see what they say.


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Not to confuse the issue but it's been my understanding that an AR15 can close on a no-go gauge and still be good to go, something to do with the difference between gauge manufacturers and "tolerance stacking".
 
1903Collector said:
Not to confuse the issue but it's been my understanding that an AR15 can close on a no-go gauge and still be good to go, something to do with the difference between gauge manufacturers and "tolerance stacking".
Click to expand...

Remsport Mfg said:
What 1903 Collector stated
What you have is kind of a Wylde chamber
Click to expand...

Yeah, but He's closing on a field gauge.
 
Remsport Mfg said:
What 1903 Collector stated
What you have is kind of a Wylde chamber
Click to expand...

All of my match rifles have Wylde chambers, none close on a no-go gauge. Nor should they. The headspace dimensions are the same, Wylde just cuts the throat a bit deeper for guys (like me) who shoot longer bullets at 600+ yards.

A brand new rifle should not close on a no-go. Period, full stop.

NO rifle should close on a field.
 
7.62x39 said:
Yeah, but He's closing on a field gauge.
Click to expand...
I know, I was just responding to what Jasons stated in an earlier post
jasons said:
All of my match rifles have Wylde chambers, none close on a no-go gauge. Nor should they. The headspace dimensions are the same, Wylde just cuts the throat a bit deeper for guys (like me) who shoot longer bullets at 600+ yards.

A brand new rifle should not close on a no-go. Period, full stop.

NO rifle should close on a field.
Click to expand...

Just so we are clear, not trying to start an argument or anything, just trying to improve my knowledge on the subject. I have seen many post on some other sites where people have stated that an AR15 can close on a SAMI no-go gauge and still be perfectly safe to shoot, there has to be a reason why people would state this whether fact of fiction.
 
1903Collector said:
Just so we are clear, not trying to start an argument or anything, just trying to improve my knowledge on the subject. I have seen many post on some other sites where people have stated that an AR15 can close on a SAMI no-go gauge and still be perfectly safe to shoot, there has to be a reason why people would state this whether fact of fiction.
Click to expand...



It's safe to shoot if it closes on a no-go gauge (as long as it DOES NOT close on a field gauge,) but if it's a brand new rifle and it closes on a no-go gauge it was probably assembled by drunken monkeys. In other words, a new rifle closing on a no-go gauge is an indication of extremely poor quality. It's a safe piece of shit, but it's still a piece of shit.
 
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jasons said:
It's safe to shoot if it closes on a no-go gauge (as long as it DOES NOT close on a field gauge,) but if it's a brand new rifle and it closes on a no-go gauge it was probably assembled by drunken monkeys. In other words, a new rifle closing on a no-go gauge is an indication of extremely poor quality. It's a safe piece of shit, but it's still a piece of shit.
Click to expand...

I'll give you an example, tell me what you think, again not trying to be a dick I just want a solid understanding of this. I have a rifle I just completed, it's a Windham barrel, 5.56 chamber (at least that's what it's stamped. BCG is LMT I think, not 100 percent sure but it's from one of the better mfgs.

My Forster no go gauge is stamped 1.4666 the bolt closes
My Forster field gauge is stamped 1.4696 the bolt does not close
So the headspace for that rifle is somewhere in between

If you look at the chart at AR15 barrels.com you see the commercial gauges listed differ from what I have and the military no go is 1.4706 so depending on what tolerances the mfgs keep too a new rifle could swallow a SAAMI no go gauge...Does that make sense? If I'm wrong I won't be offended just help me understand this because this seems to come up a lot around here.
 
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when it closes on a no go gauge your nest and last resort is a field guage.......or still safe to shoot guage.... I like jasons term better , safe pos guage.
OP dont be discouraged. Your rifle is unfired and you have recorse from manufacture (i hope) as for the M&P depending on your location I might get that checked ASAP at least S&W has life time warrenty at the momnet.
 
1903Collector said:
I'll give you an example, tell me what you think, again not trying to be a dick I just want a solid understanding of this. I have a rifle I just completed, it's a Windham barrel, 5.56 chamber (at least that's what it's stamped. BCG is LMT I think, not 100 percent sure but it's from one of the better mfgs.

My Forster no go gauge is stamped 1.4666 the bolt closes
My Forster field gauge is stamped 1.4696 the bolt does not close
So the headspace for that rifle is somewhere in between

If you look at the chart at AR15 barrels.com you see the commercial gauges listed differ from what I have and the military no go is 1.4706 so depending on what tolerances the mfgs keep too a new rifle could swallow a SAMI no go gauge...Does that make sense
Click to expand...

Personally I'd try a tighter bolt. Your rifle is safe to shoot, but it's probably not going to be as accurate as it could be and your brass won't last as long as it should. If you don't care about those things, blast away.
 
jasons said:
Personally I'd try a tighter bolt. Your rifle is safe to shoot, but it's probably not going to be as accurate as it could be and your brass won't last as long as it should. If you don't care about those things, blast away.
Click to expand...

And I don't disagree on those points, this build was basically just a back up rifle, not a match gun.
 
mac1911 said:
This statement has me a bit stumped ? do you have the head space guage for the KindaWylde Chamber...
Click to expand...

They're pretty much all "kinda" wylde. For example I know White Oak's "wylde-type" chamber is a bit different than Compass Lake's version. (Compass Lake's is a bit tighter.) None of that matters when measuring headspace.
 
jasons said:
If you're OK with it that's all that really matters.
Click to expand...

Funny thing is I have another one that does the same thing, closes on a no-go, when I drop the fired brass in my Wilson gauge they don't stretch much at all, I only have to bump the shoulder a CH....go figure.


O.P. Sorry I took the thread a little of track
 
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