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View Full Version : Headspacing a AR ?


4 Brigada
09-30-2007, 8:39 PM
Got my upper, barrel assy and complete bolt I was looking in AR15.com the build section and it said no headspace just the barrel and the bolt built to specs is good enough? Can be that easy

Fjold
09-30-2007, 8:44 PM
Yes, the headspace is set by the extension that is added on the barrel.

AJAX22
09-30-2007, 9:02 PM
If you're putting the gun togeather with used parts, its not a bad idea to check it with a field gauge... some guys sell used stuff that is a bit more 'used' than they admit to

If it won't close on a field gauge (and don't just try to hammer the bolt closed on it or let the buffer spring drive it in) you should be ok.

Randal will probalby chime in here in a bit to give you the straight skinny... listen to him, as near as I can tell he is the earthly reincarnation of eugene stoner.

4 Brigada
09-30-2007, 9:18 PM
bolt and bolt carrier are new, ADCO barrel about 300 rnds upper is a nodak retro

-hanko
09-30-2007, 10:41 PM
If you're putting the gun togeather with used parts, its not a bad idea to check it with a field gauge... some guys sell used stuff that is a bit more 'used' than they admit to

If it won't close on a field gauge (and don't just try to hammer the bolt closed on it or let the buffer spring drive it in) you should be ok.
It's easier to headspace if you remove the extractor & spring.;)

-hanko

ar15barrels
10-01-2007, 12:08 AM
Randal will probalby chime in here in a bit to give you the straight skinny... listen to him, as near as I can tell he is the earthly reincarnation of eugene stoner.

:rofl2:

I have a document that covers 223 and 5.56 headspace dimensions (http://ar15barrels.com/data/headspace.pdf).

Here is a drawing showing how the bolt, barrel extension, barrel and cartridge interact:

http://ar15barrels.com/tech/ar15bolt-extension.gif

It's true that good parts will usually headspace just fine as there is a LOT of headspace allowance built into the system.
It's also a good practice to check the headspace on all new builds and when replacing a bolt or barrel.
I also recommend checking headspace every 2k to 3k rounds throughout the life of the gun.
The only gauge you need is a field gauge measuring 1.4636" to the datum point.
I recommend clearancing the gauge on one side so you don't have to pull the ejector.