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Old June 30, 2017, 09:02 AM   #1
hounddawg
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checking the head space on a AR 15

I am getting ready to to change the barrel on a AR15 and am curious about setting the headspace. I have rebarreled several Savages but never an AR 15. Reading various articles most say that they recommend checking but it probably is not nescessary. Since I don't have a set of .223 gages I would need to buy a set. I have a .204 go gage but used the tape method for the no go . Since both use the .222 as a parent cartridge can I use the .204 and just buy a no go gage. I know .308 gages work in .250 and .243 so my first thought is yes but thought it would be best to check here before doing so.

One tutorial said to use a field length gage and if the bolt would not close you were good to go. Since no adjusment of the barrel/bolt seems to be possible would that be the most efecient way to go ? My preference would be to get a real no go for the .204 so if I ever take that barrel off again I would not have to use the tape on the go gage method

I bought a tool kit for AR's but have never tore one down, it looks to be a simple job though and I have a decent shop and a lot of experience with Savage bolt actions so I think I can manage it. All suggestions and advice are welcome
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Old June 30, 2017, 05:52 PM   #2
Scorch
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Quote:
Since both use the .222 as a parent cartridge can I use the .204 and just buy a no go gage.
The 204 Ruger does not use 222 as the parent cartridge, it uses 222 Magnum. 223 is longer than the 222 and shorter than the 222 Magnum. Get the proper headspace gauges.

Quote:
I know .308 gages work in .250 and .243
If I were you, I would check what you "know" against the real world. 308 headspace gauges will work for 243Winchester, 260 Remington, 7-08, 338 Federal, 358 Winchester, but not for 250 (I presume Savage).
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Old June 30, 2017, 06:22 PM   #3
hounddawg
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Thanks for the info Scorch, I was misinformed. Since I do not plan on building any .223 bolt guns I will just get the .223 field gage. The 250 was a typo, never even heard of that cartridge. What I meant was Remington .260


edit - looks like the .222 magnum is also the parent case for the .223. They moved the shoulder back a bit and shortened the neck. With the 204 they just necked it down to 5mm. The more I learn about this hobby the more I realize how much I don't know
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Last edited by hounddawg; June 30, 2017 at 06:40 PM.
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Old June 30, 2017, 09:17 PM   #4
Mobuck
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After assembling a couple dozen AR's, I'll simply say headspace doesn't seem to be a worrisome issue.
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Old June 30, 2017, 11:40 PM   #5
James K
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IF everyone did his part, AND the barrel and bolt lugs are NEW, there should be no problem. If not....

I understand it is now possible to rent head space gauges, do the cost is less a factor than it once was.

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Old July 1, 2017, 03:58 AM   #6
4V50 Gary
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Don't waste your money on a field gauge. Just get a no-go gauge and if it closes on that, it's out of spec (and if the bolt doesn't close on a mil-spec cartridge, then you know it just ain't right).
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Old July 1, 2017, 10:27 AM   #7
F. Guffey
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I am so lucky because I reserve the right to disagree and? This stuff does not lock me up. Head space this, head space that and ever tool is a head space gage? All I am interested in is the length of the chamber from the datum/shoulder to the bolt face.

Lucky again? My cases do not have head space, my cases have a case length that is measured from the datum/shoulder to the case head;. The difference between the two lengths is clearance; and there is verifying, I verify the gage so it does not matter what gage I use with the exception of the go-gage unless I have cut a short chamber the go-gage is going to allow the bolt to close; problem, no one knows by 'how much?' With one exception.

Reloaders are infatuated with shoulder set back, they even have a magic number of .002". I can not set the shoulder back and believe reloaders pass up a lot of good numbers when they settle on .002". and I have asked "where did that number come from?" .

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