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AR Headspace question

Discussion in 'Rifle Discussion' started by Hedrin, Apr 1, 2016.

  1. Hedrin

    Hedrin Portland area Bronze Supporter Bronze Supporter

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    Well, I finished the lower, just need to torque the castle nut down and it's done. I have a prebuilt upper from Palmetto Armory and the Sharps Balanced Bolt Carrier Group with the Relia-Bolt and the NP3 PLUS finish.

    I've looked over a number of youtube vids about checking the headspace. I don't have the tools, and frankly, I don't totally understand the process. How critical is this?

    [​IMG]
     
    Sgt Nambu likes this.
  2. old11bravo

    old11bravo Everett, Washington Well-Known Member

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    I've never checked headspace on any of my 223/556 AR builds. Always good to go with mil-spec parts. Never any problems whatsoever.

    My AR10 in .308, yes, I had the headspace checked by Rainier Arms since I bought the BCG from them.
     
  3. jbett98

    jbett98 NW Oregon Bronze Supporter Bronze Supporter

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    Unless your barrel was made by an airsoft company, I wouldn't be too concerned.
     
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  4. old11bravo

    old11bravo Everett, Washington Well-Known Member

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    BTW, sweet looking lower you've put together there!! Excellent work good sir!!!
     
  5. bolus

    bolus Portland Gold Supporter Gold Supporter 2015 Volunteer 2016 Volunteer

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    copied over from the other recent thread on this:

    Unless you are making your own barrels from scratch, the headspace is determined when the barrel is made (barrel extension is typically attached by the barrel manufacturer)

    View attachment 284862


    The barrel extension is usually already attached.

    View attachment 284863
     
  6. eldbillbo

    eldbillbo clackamas New world samurai and a redneck none the less Bronze Supporter

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    usually with mil spec parts its never an issue however some times parts are made out of spec or are mated.

    Recently i purchased a melonite "milspec" BCG that was out a spec just a little just enough to cause malfunctions that at first I thought were gas issues until i check the headspace and found that it would not close on a go gauge on newer barrels worked fine with older barrels. It rare to find issues . also some manufactures do headspace the bolts to the barrels for accuracy and can be an issue those manufactures usually note that.

    its one of those cases where the odds are you won't have a problem but if you do it could be bad.
     
  7. Hedrin

    Hedrin Portland area Bronze Supporter Bronze Supporter

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    Sorry, I looked and didn't see it!
     
  8. IronMonster

    IronMonster Washington Opinionated Member Diamond Supporter

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    That is not really accurate. You need a bolt and a barrel with an installed extension to come up with a headspace number. Its the combination of those two specific parts together that matter. You can have a barrel that will check correct with one bolt but not another or a bolt that will be good with one barrel and not another.

    One day I pulled out a dozen AR's and checked the same bolt in all of them. My National Match headspace set has like 10 gauges in .001 steps. All of them I checked with that bolt fell within the accepted range but they varied as much as 7 thou. Checked with a different bolt the readings might have been different.

    Most of the time when folks say they checked headspace they just ran go/no go gauges. In the case of go/no go then the above bolt would have just been a go in all of them. You never really would have known which was better or worse. By having a full set of gauges you can pair bolts with barrels to get the best fit and most life out of them
     
    Last edited: Apr 1, 2016
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