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Thread: headspace issue

  1. #1
    Gunco Rookie kiloechoxray's Avatar
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    Default headspace issue

    I'm putting together an all matching Polish Underfolder I got from Curtis at AK-Builder

    As I'm trying to check headspace the bolt will close on a live round no problem but wont close on a 'go' gauge or a 'no-go' gauge.

    Since the barrel was pre-headspaced by Curtis' shop I'm at a loss for what might be the issue here.

    Any ideas?

    thanks

  2. #2
    gunco irregular moleman's Avatar
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    There are differences between sammi spec gauges and the originals, as well as the methods used to check headspace (some methods use a specific weight to aid in closing). I just check it with a stripped bolt only, and again with the carrier and the stripped bolt, and a squeaky clean chamber. If it closes on your ammo it sounds like it is headspaced on the tight side. I would shoot it and check your headspace again after a 100 or so rounds if it concerns you.

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    GuncoHolic 2ndAmendican's Avatar
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    Yeah it sounds like it's headspaced on the tight side. I agree with mole. Shoot it and recheck.
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    Gunco Rookie kiloechoxray's Avatar
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    Thanks for your input guys. I trust Curtis headspaced these barrels to the trunions correctly, especially since the ammo is manually cycling (coming out of the mag, into the chamber and ejecting fine) Rounds are going into battery and bolt is locking.

    My go gauge is a little weird - chipped on the rim portion, so I've wondered if thats affecting it, but I can't reason why it would. Its just missing material on the rim portion of the gauge.

    Having built several AKs in the past and being a Mech Eng, my guy says its fine - but my brains says check with you guys since you may very well have more knowledge than me that I can learn from

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    GuncoHolic 2ndAmendican's Avatar
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    No problem. Let us know how it works out.
    Enforcement, NOT Amnesty!!!!!!

    "If they’re going to come here illegally, apply for & receive assistance through a corrupted Government agency encouraging this lawless behavior, work under the table & send billions of dollars each year back to their families in Mexico, while bleeding local economies dry, protest in our streets waving their Mexican flags DEMANDING rights, while I have to press ’1′ for English, then they need to be shipped back to where they came from!" -Chad Miller

  6. #6
    Gunco Rookie kiloechoxray's Avatar
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    Will do

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    3/6 Infantry mtdew's Avatar
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    It will be fine. I actually like to headspace a little tight. They seem to loosen up after several rounds fired.
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    Diss Member netpackrat's Avatar
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    I am pretty sure my Forster headspace gauges are SAAMI spec instead of CIP. The "go" gauge will not fully chamber in any AK that I have tried. After building enough of them, I know about how far the bolt should close on it.
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  9. #9
    Gunco Rookie kiloechoxray's Avatar
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    Quote Originally Posted by netpackrat View Post
    I am pretty sure my Forster headspace gauges are SAAMI spec instead of CIP. The "go" gauge will not fully chamber in any AK that I have tried. After building enough of them, I know about how far the bolt should close on it.
    What is the difference between the SAAMI and CIP?

    I'll have to check my guages to see what they are. I know I bought them from Brownells.

    Do you have a method for installing the barrel to proper headspace if its a virgin barrel?

  10. #10
    Gunco Regular jimraynor21's Avatar
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    Quote Originally Posted by kiloechoxray View Post
    Do you have a method for installing the barrel to proper headspace if its a virgin barrel?
    I put the lower handguard retainer on my barrel, made a straight edge to line up the top of it with the top of the front trunnion, eyeballed the extractor cut and pulled the barrel in. I got it close by judging where the previous barrel had been pressed in based on the surface inside the trunnion(very shiny/obviously made contact with another metal part). Then start testing the bolt with the gauges, pressing it further in/backing it out accordingly. Then drill/ream your barrel pin hole once satisfied.


    I also made several clean marks with red nail polish on the trunnion/barrel once I had the barrel pin hole drilled so it was easy to line up again after riveting the front trunnion in.
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