basicaly, if you only own one gauge, i would say it should be a field gauge. as long as it wont chamber you know you have less then the maximum headspace, and if you had less then then minimum then a round in theroy should not chamber.

I also have a no go field gauge...but I have a question. Why should we have to remove the firing pin, ejector, and extractor from the bolt? If you can not get the bolt to close on the gauge then all is well...even with those components installed...correct?

Obviously you wouldn't want to slam the bolt closed with the gauge in...but I really don't see why the bolt has to be disassembled as long as you are careful.....but then I am not a smith

Thanks for the schooling!!

If you had multiple barrels/bolts to test, is there a way to check headspace without removing the ejector?

My first thought would be to have a professional machine a hole in the gauge so the ejector doesn't push on the gauge.

Pros and cons?

That is incorrect.

There are just gauges. Of different sizes. Period. They are USED to follow different specifications of "go" and "no go". They are "loosely" defined as Civilian, or Military. Also can be considered SAAMI vs NATO.... as in the chamber dimensions. GENERALLY - a bolt gun will have a SAAMI chamber, and a gas gun will have a NATO chamber, but that is not always the case.

This isnt really as complicated as people make it... because as I have stated - loose headspace is not a big deal unless it is ridiculous....

Gauge differences organized by type:


Gauge    Civilian   Military   Difference

GO       1.4640"    1.4646"    +0.0006"

NO-GO    1.4670"    1.4706"    +0.0036"

FIELD    1.4700"    1.4730"    +0.0030"

FIELDII  1.4736"    N/A        N/A



 

Just to show the differences in headspace specs…

M249 SAW GO       1.4949    -0.0002"   1.4940" - 1.4947"

M249 SAW NOGO  1.4982    -0.0002"   1.4982" - 1.4980"

M249 SAW FIELD   1.50216  -0.0002"   1.50216" - 1.50196"

Taken from: http://www.ar15barrels.com/data/headspace.pdf

maybe one of you can help. i finally got around to my first ar build this past weekend and found that my head-space is to tight. im not sure on the brand of go gauge we used but it would not chamber. i will go back by my friends later and try it again not that i have really scrubbed out my boar and chamber. before it would not always chamber lake city and it was a tight extraction and not they are smooth so it could have been gunk. im not sold on this. so i will post back when i know the brand of gauge. hopefully it will chamber but i have a feeling it wont.

Dannel defense 16inch chrome lined 5.56 barrel http://www.bravocompanyusa.com/Daniel-Defense-16-M4-Carbine-Gas-Barrel-stripped-p/dd%209060.htm

bravo company manufacture complete bolt Assembly http://www.bravocompanyusa.com/BCM-Bolt-Carrier-Group-MPI-Auto-M16-p/bcm%20bolt%20carrier%20group%20auto%20mp.htm

and a Yankee hill upper http://yankeehillmachine.com/store/product368.html with there barrel nut. that that the upper or nut really matter (i think maybe im wrong)


so since i have a chrome lined boar what do i do?

i have tried the bolt from my old bushmaster and it was having the same issues with some brass. although i did not have the gauge. so i will try my bushy bolt with the gauge as well as some of my friends bolts.

assuming these dont work what is the next step? i was thinking of getting a piece of brass and some polishing compound and lapping the chamber?

hopefully one of you can help, as i am afraid i am sol. my friend who is a colt armor is stumped and has never heard of this actually happening.

Answered earlier in thread. Delete.

I'd recommend BCM or LMT. You get the right price and quality mix. You should be able to find both at bravocompanyusa.com

It's done as you describe. I think the idea is to mate the threads of the barrel nut and upper, to get an accurate torque. Whether it's really necessary may be debatable, but it only takes a few minutes.

yes, there is barrel break in processes, lots of different options and opinions on this, i have my method but u might want to do a search and find one that u like

Well I was an armorer in the Marine Corps trained at aberdeen proving grounds ... we never disassemble the bolt for this ... you just use pressure at the back of the carrier and make sure it travels as far as it can go .

I'm sorry if this has been asked but in theory wouldnt you only need a field or no-go guage. If it closes on them you make need to look further into it but what do you gain from a go guage if it doesnt close on that wouldnt you have a problem chambering a round? I'm just trying to decide what I'm going to do with a upper I built that has a new barrel and used bolt (about 400 rds).

Thanks for the help.