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  1. #1
    Join Date
    Jun 2011
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    256

    Adjusting for headspace in an AR

    So I figured this would be a good place to ask. How hard is it to adjust for headspace in an AR if I start with a stripped upper? How is it done? If I bought an upper without a BCG and charging handle would I need to do it? Thanks.

  2. #2
    Join Date
    Sep 2012
    Location
    NY
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    1,471
    Quite hard to do. Almost all AR builds will go together without you having to adjust head spacing.

  3. #3
    Join Date
    May 2012
    Location
    Chemical Valley, West Virginia
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    169
    When you say stripped upper, do you mean it's just the stripped upper receiver without the barrel? When the barrel is fitted to the reciever it should be checked with Go and No-Go guages to check and make sure the headspace is correct. If the upper already has the barrel properly fitted, then you should just need the BCG and charging handle, no need to headspace it.
    4-DT-S
    Izula DT

  4. #4
    Join Date
    Sep 2012
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    Socialist Republik of Obama
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    303
    If you buy quality name brand parts like DD/RRA/WMD, you wont even need to check head space.
    However if you were so inclined to get an offbrand Itchypuzy BCG or barrel adapter from China, well then I'd seriously consider checking with Go/No-go gauges.

  5. #5
    Join Date
    Feb 2012
    Location
    Michigan
    Posts
    1,311
    For the cost of go no go gauges get a set you can always resell for 80% the cost or put it together and just have a gunsmith check it.

    Quality parts should go together just fine with out issue, but for a few bucks I would double check to save my face.

    Sent from my SPH-D700 using Tapatalk 2

  6. #6
    Join Date
    Sep 2012
    Location
    NY
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    1,471
    Quote Originally Posted by DiscoveryLover View Post
    When you say stripped upper, do you mean it's just the stripped upper receiver without the barrel? When the barrel is fitted to the reciever it should be checked with Go and No-Go guages to check and make sure the headspace is correct. If the upper already has the barrel properly fitted, then you should just need the BCG and charging handle, no need to headspace it.

    Not entirely true.

    The headspace is set from the Bolt face and the barrel, technically any time you switch out a BCG you should be checking headspace.

    Most people don't check headpace on an AR build because with modern machining the guns are almost always in tolerance but you still should be checking it.

  7. #7
    Join Date
    Jan 2012
    Posts
    309
    The things which factor into headspace are A] depth of the chamber in relation to the bearing surfaces of the barrel extension's eight splines (where they contact the bolt lugs) and B] the depth of the bolt's cartridge seat in relation to the bolt lugs' bearing surfaces (where they contact the extension splines)

    You should check headspace any time you change the bolt, and any time you remove the barrel extension from the barrel (the extension is rarely removed from the barrel).

    In the event of a headspace problem, the quickest and cheapest fix would be to get a different bolt with the cartridge seat cut deeper or shallower depending on which direction headspace is off.

    Reaming the chamber deeper is best left to pros (and their very expensive chambering reamers). Altering the barrel shoulder and/or barrel extension can work but it's a pain, and a big adjustment could change the thread timing, i.e. your front sight might become tilted in relation the the barrel extension's index pin.

    Chances are you'll never see a headspace problem in an AR rifle, but it's not completely unheard of. Gages are fairly cheap.
    Just because you're paranoid does not mean they're not out to get you.

  8. #8
    Join Date
    Jun 2011
    Posts
    256
    Okay I think I understand a little better now. I'm pretty sure whatever upper I get will have the barrel attached. I just happened to see one that did not come with the BCG. If I did end up going that route then I would take it to a gunsmith more than likely. I hadn't considered that before.

 

 

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