Headspace gauges in 5.56mm: bolt dissassembly?

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[ARCHIVED THREAD] - Headspace gauges in 5.56mm: bolt dissassembly?

Posted: 8/14/2005 3:33:21 PM EDT

I found the following headspace gauges below.

It appears that the base is rebated so that the case extractor will fit around the gauge. When I check headspace on my Garands and M1As, I dissassemble the bolt: nothing is in the way to interfere with fit.

Does the AR bolt need to be dissassembled to check headspace?

I am mating a new Bushmaster barrel to a new Stag/CMT bolt.

I prefer to check headspace before firing it, then check the case size with a Mo's Gauge.

Posted: 8/14/2005 3:54:19 PM EDT

[#1]

It is better to remove the ejector and extractor before using the HS gages. Place the gage in the chamber and gently try to close the bolt/bolt carrier assy into battery using finger pressure. Charles.

Posted: 8/14/2005 6:16:51 PM EDT

[#2]

I always dissasemble the bolt and use finger pressure also, but I only use a field guage.

Posted: 8/18/2005 8:17:52 PM EDT

[#3]

It would be nice to have headspace gauges that where narrowed at the base, so the bolt would not have to be dissassembled. I made some from standard headspace gauges, by putting them in a lathe and cutting them down. Saves tons of time and effort. I use them for a quick check: "GO" and "NO GO", not for 0.001" incremental chambering. Looks like, I'll be doing the same thing with the AR.

Posted: 8/18/2005 8:53:17 PM EDT

[#4]

USGI field guages dont require the bolt to be disassmebled, and I seriously doubt their would be anything wrong with the headspace of the build in question.

Posted: 8/19/2005 1:28:43 AM EDT

[#5]

I thought the same thing: everything will be OK. I am using known quality parts: Bushmaster barrel assembly and a Stag bolt/bolt carrier.

Where does one find a USGI field gauge?

Posted: 8/19/2005 2:07:17 AM EDT

[#6]

The military style ones used to show up in Shotgun news at different places but I have not seen any in a while. There are a few places to get the ones made to military length but they still require bolt disassembly (Brownells and Fulton Armory). Hopefully someone will post a source for the one with the reduced rim. I sure would like to have one also.

Posted: 8/19/2005 2:17:42 AM EDT

[#7]

Guys you don't have to look too far, brand new in the wrapper GI field headspace gages at the EE for $25 shipped.

Good luck.

NIW USGI 5.56mm FIELD Headspace gages $25 shipped EE link

Posted: 8/19/2005 2:54:52 AM EDT

[#8]

don't mix brands of HS gages.

USGI FIELD gages have rebated rims to clear the ext/eje. USGI GO and NOGO gages do not have rebated rims.

You can cut a notch for the extractor yourself if it's a concern. I prefer to leave the ext/eje in place and use unmodified gages as it speeds up the operation.

I recommend that people who do not know what finger pressure means strip the bolt before checking their HS.

DO NOT drop the bolt onto a gage as that is sure way to make even the longest gage fit into the chamber regardless of the HS.

ALWAYS check that the ejector telescopes fully beneath the face of the bolt and that the ejector can move far enough aside to clear the rear of the gage/cartridge BEFORE checking the HS.

You shouldn't need a FIELD gage on a new build, FIELD gages are for checking rifles that have already seen service hence already been checked with a GO gage. You will want a GO gage like those used by every factory in existence.

Posted: 8/19/2005 4:21:41 AM EDT

[#9]

Thanks for the link.

I always check with a go and a field even on a new build. Bought to many bad parts over the years.

Posted: 8/19/2005 5:39:21 AM EDT

[#10]

Quoted:
The military style ones used to show up in Shotgun news at different places but I have not seen any in a while. There are a few places to get the ones made to military length but they still require bolt disassembly (Brownells and Fulton Armory). Hopefully someone will post a source for the one with the reduced rim. I sure would like to have one also.

USGI field guages dont require disassmebly. I dont have to on mine

Posted: 8/19/2005 6:14:27 AM EDT

[#11]

USGI field guages dont require disassmebly. I dont have to on mine

Who said the they did?

Posted: 8/20/2005 5:36:34 AM EDT

[#12]

Quoted:
don't mix brands of HS gages.

USGI FIELD gages have rebated rims to clear the ext/eje. USGI GO and NOGO gages do not have rebated rims.

You can cut a notch for the extractor yourself if it's a concern. I prefer to leave the ext/eje in place and use unmodified gages as it speeds up the operation.

I recommend that people who do not know what finger pressure means strip the bolt before checking their HS.

DO NOT drop the bolt onto a gage as that is sure way to make even the longest gage fit into the chamber regardless of the HS.

ALWAYS check that the ejector telescopes fully beneath the face of the bolt and that the ejector can move far enough aside to clear the rear of the gage/cartridge BEFORE checking the HS.

You shouldn't need a FIELD gage on a new build, FIELD gages are for checking rifles that have already seen service hence already been checked with a GO gage. You will want a GO gage like those used by every factory in existence.

Excellent points.

Posted: 8/21/2005 1:24:47 AM EDT

[#13]

Thank you, I learned to refine them after the first couple hundred re-posts.

[ARCHIVED THREAD] - Headspace gauges in 5.56mm: bolt dissassembly?

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