[otubrab]

Quote:       Originally Posted by golem1961

all I,m saying is that you can not affect headspace by barreling an ar15 upper receiver

Inaccurate:
Putting a new barrel in an existing barrel extension will change headspace unless the chambers of the two barrels and the outside thread/shoulder profiles are identical. Rarely happens.

Putting a new barrel/barrels extension combination on an existing reciever will cause a headspace change unless the front of the lugs on extension and the chamber shoulder datums of the barrels are the same relative to the bolt.

If you move an existing bolt and barrel/extension comb to a new reciever, the headspace should not change.

Whenever you change bolt, barrel extension, or barrel you will change headspace. The question is, is the change consequential? You've got to check it to know.

[SwedeSteve]

Thanks for the great info.

[Redbeernuts]

I like this guy ^

[SwedeSteve]

One arrow would indicate me !! Surely not what you intended !! If you wre referring to otubrab then it would be ^^. Two posts above !!

[specop425]

hey guys, new here. sort of new to ar's. how big of a deal is this? I just assembled an upper, but have not fired it yet. this is a s.h.t.f. weapon and will more than likly sit in my closet forever but better to have it and not need it than need it and not have it. any who. I have a free float tube. I tightned it till the gas tube hole lined up. could I really have problems if all is not good by 1/1000 of an inch? again I dont know alot about the fine detales but it seems kind of silly to me that a combat oriented weapon could be so picky.
(sorry about the spelling Im dyslexic as all get out)

[gun monkey]

Only if it's .001 to tight, it safer to be alittle long. If this was a match bolt gun then its a different story. An easy way to check any firearm is to buy a cheap pair of dial calipers and measuring your fired case to an unfired case. Check to outer diameter (OD) of the case body, and to over all length. A go gage will not show you that the chamber diameter is to large just that it is the correct depth. If the case OD is .005 or greater over unfired it would be best to have it looked at by a gunsmith. Most factory guns run around .003 over, match grade will be less than .0015.

[tommy]

maybe thats what they mean when they say made to specs!!!! specs meaning headspacing and everything . when they make something to specs it's gonna match up with any part made to the same specs . now if you have an upper or a lower that isn't made to specs then you have a problem.

[Sprout47]

**looks for his GO/NO-GO gauge but can't find it**

[gun monkey]

Quote:       Originally Posted by tommy

maybe thats what they mean when they say made to specs!!!! specs meaning headspacing and everything . when they make something to specs it's gonna match up with any part made to the same specs . now if you have an upper or a lower that isn't made to specs then you have a problem.

I've seen factory new guns that a no-go or field gage would fit in the chamber, not common but have seen it. And if the barrel wasn't running true to the bore when it was reamed for its chamber then the head space can be correct with the chamber itself larger than spec..

[DaTeacha]

Oh boy, this is good stuff for an ignorant guy like me. I'm building an AR, like many here. I have the lower pretty much done, but am making my own stock out of wood. I have a semi-stirpped upper that has the forward assist, dust cover and charging handle in place. I have a bolt carrier and bolt ordered from SOG. I have a GO gauge and a FIELD gauge, both from Midway (maybe Brownell's, can't remember right now). I have read and refer to Walt Kuleck's book. I have pretty decent mechanical skills, tools, etc. I am planning to install a sightless barrel and low profile gas block when I can find the barrel I want. If my assembly swallows the FIELD gauge, I will not be a happy camper and will plan to return the barrel. I prefer a tight chamber.

In looking at barrels in catalogs and on line, I find myself wondering if the barrel extension and the assortment of springs, washers, clips, etc. that are used to attach the barrel to the upper is included with the barrel. I have emailed customer service at Midway about this but got no response, unless my filters won't let it through. Can you guys help me out here a little with some information? Thanks!

[wunhunglo]

Quote:       Originally Posted by DaTeacha

Oh boy, this is good stuff for an ignorant guy like me. I'm building an AR, like many here. I have the lower pretty much done, but am making my own stock out of wood. I have a semi-stirpped upper that has the forward assist, dust cover and charging handle in place. I have a bolt carrier and bolt ordered from SOG. I have a GO gauge and a FIELD gauge, both from Midway (maybe Brownell's, can't remember right now). I have read and refer to Walt Kuleck's book. I have pretty decent mechanical skills, tools, etc. I am planning to install a sightless barrel and low profile when I can find the barrel I want. If my assembly swallows the FIELD gauge, I will not be a happy camper and will plan to return the barrel. I prefer a tight chamber. In looking at barrels in catalogs and on line, I find myself wondering if the barrel extension and the assortment of springs, washers, clips, etc. that are used to attach the barrel to the upper is included with the barrel. I have emailed customer service at Midway about this but got no response, unless my filters won't let it through. Can you guys help me out here a little with some information? Thanks!

Normally the barrel is supplied bare with the Extension fitted to it. Nothing else.

[tommy]

so what your sayin is the gun wasn't asembled and manufactured corectly to specs right?? it it was the problem wouldn't be happening.

Quote:       Originally Posted by gun monkey

I've seen factory new guns that a no-go or field gage would fit in the chamber, not common but have seen it. And if the barrel wasn't running true to the bore when it was reamed for its chamber then the head space can be correct with the chamber itself larger than spec..

[gun monkey]

Quote:       Originally Posted by tommy

so what your sayin is the gun wasn't asembled and manufactured corectly to specs right?? it it was the problem wouldn't be happening.

Tell me what is the spec? For and AR rifle do you mean Mil-Spec? No civilian can own a Mil-Spec part, it might be made to the same print but it can't be a true Mil-Spec because the government is not going to inspect it. So please tell me how the manufacturer checks the internal dimentions or the chamber other than headspace. Now if it doesn't head space correctly then you are correct 100%, but if it does then it is in spec, what I said in my original post here was to buy cheap pair of dial-calipers to check the OD of the fired case, this wouldn't hurt to do to all of your guns. If you know of another way it check this please let us know.

[azguy]

Am I to asume (really bad word) that if I stick to the same manufaturer for the upper receiver and barrel assembly, and put them together correctly I am less likely to run into problems when I test "headspacing" with the GO/NO-GO gauges? If I am lucky enough to get a pass on the GO gauge, and a fail on the NO-GO gauge, do I still need to get a pass on the FIELD gauge to get a properly assembled upper receiver? Or does the FIELD gauge test only need to be preformed if I get a failed with the GO gauge?

[DaTeacha]

I was just going to ask that. I have been presuming the smallest gauge is the GO, the next is the FIELD, and the biggest is the NO-GO. I need to read the section in Kuleck's book again when I'm more awake, but it almost sounded like the FIELD was the longest gauge.

I want my gun to close on the GO, but not close on the other two. Which is bigger, FIELD or NO-GO?

This gets a little confusing when they talk about pass or doesn't pass. Why not keep it simple with 'closes' or 'won't close'?

[azguy]

As good as Kuleck's book is it can be vague in parts. I am just going to have to buy an AR Build DVD and watch it to make sure. It's kind-of-like following a Chilton repair manuel when doing home auto repair, the author assumes knowledge where there is none, and goes into great detail on simple things that are a waist of paper. It seams pretty straigtforward and simple, drop the guage into the breach and see if the bolt closes, but never having done it before there is no 100% confidence on my part. This simple test seams to be the moment of truth, for the entire build. And it is the one part I know you cannot fudge your way past. But as most things the devel is in the details.

[Orlando]

If it closes on the No Go it needs to be checked with the Field Gauge. If it closes on the Field gauge you have excessive headspace

[DaTeacha]

So then the Field Gauge is bigger. Now I have to wonder why they have a NO GO if you can still use it even though it closes on that gauge, even if only in an emergency situation. Time to order a NO GO gauge. When I ordered them originally, I thought the FIELD was the middle one.

[Orlando]

The Field gauge is what you use to keep a eye on headspace when a bolt fails the NoGo.

[jsh3fan]

I have actually built hundreds of these, never once have I had any headspace problems, I've checked the headspace with a go guage and a no go, just for just in case something wasn't machined quite right, but never once did I have a problem, with headspace, to me on ar's fit the barrel to the receiver and torque the barrel nut and finish out the upper, I have sold alot of uppers and fully complete rifles never once did anybody come back to complain, believe it if something was wrong they would come back and say WTF, each and every rifle or upper I put together. Each one I built was test fired.