Another DUMB question

W

William Suter

Well-known member
OK, here goes. How do you head space an AR? I'm well aware on head spacing a bolt action rifle barrel but don't have a clue on head spacing an AR barrel. Sorry if its a dumb question but I've said time and time again, I'm no AR guy. Even though now I have one.
 
The stripped bolt and headspace gauges are used to check the extension/barrel after they are mated. Normally before the assembly (upper/barrel) occurs. As you need to check(feel) amount of rotation of the bolt in the extension. If you need to replace the bolt, you can measure the depth of the bolt face to confirm headspace is not changing.
 
Unless you’re replacing the bolt or barrel, or both it shouldn’t be necessary. That should have been done when it was built. If you’re just curious or checking, it is as SSS stated. The easiest way is with the proper caliber go – no/go gauges.

Strip the bolt of the extractor and ejector. With just the upper clamped in your vise, insert the go gauge in the chamber, insert the bolt, it should fit in and turn locking the lugs. A slight resistance is fine. Then insert the no/go gauge. It should not fit and turn.
 
Reason for asking is if I ever replace my barrel. But if I change to a different cartridge, like a 22 ARK, then a different bolt will be necessary anyway. If I go that route, I'll just buy a complete upper.
 
Headspace is set (and checked) by whoever installs the barrel extension (generally, the barrel maker). It should be correct, but I suppose it is possible to have a really worn, or out-of-spec bolt.
 
Common to purchase a bolt with new custom barrel or send in your bolt to be HS with new barrel. As I mentioned most bolts are to mil spec and are interchangeable (in cartridge family). I do have a Bushmaster 223/556 bolt that is minimum HS, so it doesn't swap with my other 223's. I actually purchased a couple more bcg so I didn't need to swap around between uppers and I could leave the bushy in one piece.
 
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