AR15 headspace gauge - without disassembling the BCG?

[tRidiot]

I've decided to go ahead and get the proper equipment to check headspace on my rifles. I've never bothered with checking it and it's never been a problem before, but I'm at the point now where I want to get into the smaller, less well-known tidbits of putting together my own Frankenguns - things like headspace measurement, gas key staking, etc.

EVERY commercially-manufactured headspace gauge I've been able to locate requires at least the extractor be removed from the BCG and some require both the extractor AND ejector. However, I understand the old military headspace gauges didn't require this, as they were "notched" somehow to allow proper headspace measurement without ANY bolt disassembly. These seem to have dried up or are ridiculously expensive. Any why the hell doesn't a commercial manufacturer fill this niche???

Several people have mentioned making their own out of a commercial gauge by cutting a notch in it somehow, but I've not been able to find any good pictures or DIYs on how to do this properly without damaging my headspace gauge and rendering it useless. Old archived threads on the subject generally seem to have outdated or broken links and pictures.

Do any of you guys have one of these headspace gauges you've modified to allow use without any bolt disassembly, or can explain to me exactly what it is I need to do?

<note> I realize bolt disassembly isn't a huge complicated process, but my thought is, if it doesn't NEED to be done, why do it?

 

[mr ed]

the barrels are chambered and the barrel extension fitted to an industry standard. the bolts and carriers are made to the same standards. therefore there is no need for people to have the gauge. the only reason to have a gauge is if you were building a custom barrel and fitting the extension yourself. its a whole lot easier for you to measure a fired case versus industry specs. just add .005" -.007" for stretch due to the "slop" required for a semi auto to function.
a semi-auto with zero excessive headspace will not function, unlike a bolt gun where you can force the bolt home when it jams up on powder fouling.

 

[MoBoost]

I have notched my gauges for extractor with a dremel. I am sure you can just drill a hole for the ejector as well.

 

[tRidiot]

the barrels are chambered and the barrel extension fitted to an industry standard. the bolts and carriers are made to the same standards. therefore there is no need for people to have the gauge. the only reason to have a gauge is if you were building a custom barrel and fitting the extension yourself. its a whole lot easier for you to measure a fired case versus industry specs. just add .005" -.007" for stretch due to the "slop" required for a semi auto to function.
a semi-auto with zero excessive headspace will not function, unlike a bolt gun where you can force the bolt home when it jams up on powder fouling.

I appreciate your sentiment... that most of them should work together and be just fine. However, I am looking to measure the headspace. It's a relatively cheap tool and is simply a little more peace of mind. I realize it's probably not "necessary"... but it's not going to hurt anything, either.

I have notched my gauges for extractor with a dremel. I am sure you can just drill a hole for the ejector as well.

Don't suppose you've got any pictures?

 

[Hump66]

I believe there is a difference between .223 and 5.56 gauges, just something to consider.

 

[uncle money bags]

I believe there is a difference between .223 and 5.56 gauges, just something to consider.

You would be correct. Here is a pdf for the op and any one else who is interested.

www.ar15barrels.com/data/headspace.pd.

 

[tRidiot]

Yes, I know .223 and 5.56 gauges are different. I'm just trying to figure out how to modify one so the extractor and ejector do not have to be removed. Or find one commercially available.

Anyone?

 

[338Shooter]

Getting into the intricacies but won't remove the two pins for extractor and ejector? Literally 2 extra minutes.

 

[ASP785]

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

This was the only source I have seen an actually USGI gauge from. You are a few months too late though as they are sold out. If memory serves me, they were around $40.

You might look into getting a bolt takedown fixture to make the process of ejector and extractor removal a little more streamlined.

http://www.brownells.com/gunsmith-t...locks/sinclair-ar-15-bolt-vise-prod34719.aspx

 

[tRidiot]

Getting into the intricacies but won't remove the two pins for extractor and ejector? Literally 2 extra minutes.

I'm really tryin'ta bite my tongue on this one... This isn't ARFCOM, but sometimes we just like to play like it is, hmmm?

Thought I covered that in the last line of my first post, but some folks just can't help but point out their superiority to others, I suppose.