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Headspacing an AR 15 upper during the build... Q's

BigDanSBigDanS Senior MemberPosts: 6,973 Senior Member
I just watched Larry Potterfield build and AR upper. In the process he head spaced the bolt in an AR 15 barrel. He used a completely disassembled bolt and headspace gauges, which was very straight forward.

I, however, have a pre-assembled bolt, a factory barrel and no headspace gauges.

I would prefer not to disassemble the bolt and buy a set of headspace gauges.

Thoughts and opinions, please?

D
"A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:

Replies

  • Elk creekElk creek Senior Member Posts: 6,462 Senior Member
    Put it together and shoot it. If you are using quality parts from a reputable maker there should be no problem.
    Aim higher, or get a bigger gun.
  • BAMAAKBAMAAK Senior Member Posts: 4,484 Senior Member
    Simple pictorial on how to take the BCG apart

    http://www.ar15.com/forums/t_3_7/456002_FIELD_STRIPPING_THE_AR15.html
    "He only earns his freedom and his life Who takes them every day by storm."

    -- Johann Wolfgang von Goethe, German writer and politician
  • Elk creekElk creek Senior Member Posts: 6,462 Senior Member
    cpj wrote: »
    This.
    Side note, his smile creeps me out.
    X2
    Aim higher, or get a bigger gun.
  • ZeeZee Senior Member Posts: 24,018 Senior Member
    If you own an AR.......you better know how to take the BCG apart.
    "To Hell with efficiency, it's performance we want!" - Elmer Keith
  • ZeeZee Senior Member Posts: 24,018 Senior Member
    I've got a set of Go/No-Go Gauges and I've never used them to build an AR. I just build it, cycle some rounds through it.........then shoot it.
    "To Hell with efficiency, it's performance we want!" - Elmer Keith
  • tennmiketennmike Senior Member Posts: 27,398 Senior Member
    I'm a little confused, Dan. Are you assembling a barrel to an upper receiver?

    Anyway, while not exactly recommended procedure, you can use factory brass like CPJ said. What I'd do without a headspace gauge is remove the extractor. Ain't no biggie; just do it. Install the barrel. Drop a piece of factory brass in the chamber. If you don't have factory brass, then pull a bullet from a round and make sure no powder remains in the case. Slide bolt into battery by hand. If it closes and locks up, remove case and put a couple of pieces of cellophane tape on back of case head, and try to close bolt again. If it closes headspace is a little generous, but if it doesn't close and lock, then you're good to go.

    And the reason you want the extractor removed is because it can drive the brass into the chamber and give a false reading.

    You have a Bass Pro Shop close down there if I remember correctly. You could call and see if they can check the headspace for you. Might cost a few bucks, but would give you peace of mind. Just a thought.
      I refuse to answer that question on the grounds that I don't know the answer”
    ― Douglas Adams
  • Farm Boy DeuceFarm Boy Deuce Senior Member Posts: 6,083 Senior Member
    Dan,

    Assemble the upper. Then strip the bolt. Then find a 'smith and just pay him a couple bucks if it worries you.


    Or assemble the upper hand cycle some dummy rounds through it. Then go shoot a few rounds through it. If it will make you warm and fuzzy measure the spent brass.

    I have assembled three uppers (without headspace gauges) so far and have not rearranged my beautiful face.

    IM inbound.
    I am afraid we forget sometime that the basic and simple things brings us the most pleasure.
    Dad 5-31-13
  • HvyMaxHvyMax Senior Member Posts: 1,786 Senior Member
    Larry is grinning like that because he can smell the money you are going to be sending him!!!
    Wal Mart where the discriminating white trash shop.
    Paddle faster!!! I hear banjos.
    Reason for editing: correcting my auto correct
  • BigDanSBigDanS Senior Member Posts: 6,973 Senior Member
    Thanks. Looks like I need to take my bolt apart anyway...

    D
    "A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
    Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:
  • BigDanSBigDanS Senior Member Posts: 6,973 Senior Member
    I have a Wheeler Engineering AR build kit I bought off WOOT! for $40 that has most of what I need to do this. I think I need a roll punch starter and a set of roll pin punches. Everything else looks pretty simple.

    I believe I am going with a Diamondhead VRS™ "T" 13.5" Free-Floating Versa Base I can get delivered for $150. Now I need to find a set of front and rear BUIS, and the correct mount. I believe I will use my Weaver 1-4x scope with it. I also need brass, and dies. I have 125 gr Speer .308's to make some bullets.

    D
    "A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
    Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:
  • BigslugBigslug Senior Member Posts: 8,262 Senior Member
    A 5.56 NATO "field" headspace gauge is a good thing to have around to check for excess. It's a whopping $23 http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/5-56mm-maximum-headspace-gauge-prod6646.aspx For a "go" gauge, a cartridge will suffice, as the only real purpose of a min/go gauge is to make sure the bolt will close on a round.

    The "thou shalt not exceed" tolerances in AR parts production are USUALLY pretty well adhered to, and you can USUALLY throw parts together willy-nilly and have the gun gauge out OK - at least if the main parts are all coming from one manufacturer. OTOH, it's over 50,000 PSI, and it's right next to your face. When other people and explosives are involved, I ain't real big on trusting to faith.

    Such is the joy of building one rifle "on the cheap". By the time you're set up with the punches, torque wrenches, vise blocks, alignment and headspace gauges to do it justice. . .not so cheap.
    WWJMBD?

    "Nothing is safe from stupid." - Zee
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