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AR15 7.62x39 cycle issues

Discussion in 'General Firearm Discussion' started by GMC Z, Nov 20, 2015.

  1. GMC Z

    GMC Z New Member

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    Built an AR chambered in 7.62x39. Test fired it for the first time today, fires one round, ejects the brass cleanly, but doesn't chamber the next round. I have a rifle length gas tube on a 20" barrel. Most forums I've read recommend opening up the gas port in the barrel, I've also read a couple that recommend changes in the weight of the buffer or springs. Leaning towards opening up the gas port, does anyone here have real world experience and recommendations? What size should the gas port be? Haven't taken any thorough measurements, but the round end of a 1/8" drill bit will not fit. Using an ASC 30 round magazine. Everything works when I cycle it manually.
     
  2. erudne

    erudne The Pie Matrix PPL Say Sleeping W/Your Rifle Is A bad Thing? Bronze Supporter

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    1st disassemble and dry lube your mag, check mag catch to see if the catch is screwed even with the release button, check for burrs and dents in mag. Lube your recoil spring w/lithium grease. inspect your bolt and bolt locking recesses for burrs etc. Gas key correct? Is your ammo reloaded?
    If the above are to spec try to locate an adjustable gas block and install.:p
     
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  3. Dyjital

    Dyjital Albany, Ore Flavorite Member Bronze Supporter

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    Verify your gas port is in the right spot on the gas block. It may go back far enough to eject but not to pick up another if they are misaligned.
     
  4. Certaindeaf

    Certaindeaf SE Portland Well-Known Member

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    One round? Probably all corroded.













    Just kidding!
     
  5. DRZ400S

    DRZ400S Washougal, WA. Active Member

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    Did you try just one round in the magazine? If it locks back gas port is fine.
     
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  6. GMC Z

    GMC Z New Member

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    I'll give that a try.
     
  7. GMC Z

    GMC Z New Member

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    Checked it. Applied a little lock tight to the area to improve the seal, no change.
     
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  8. GMC Z

    GMC Z New Member

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    Will give it a try.
     
  9. bakersman345

    bakersman345 Camas wa Well-Known Member

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    File down the m4 feed ramps to make a smooth feed ramp like the ak-47 has. Buffer spring mine was too light to chamber the next round
     
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  10. Dyjital

    Dyjital Albany, Ore Flavorite Member Bronze Supporter

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    after fired will it lock the bolt back?
     
  11. GMC Z

    GMC Z New Member

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    Problem solved. Fired it with a single round, the bolt did not lock back. Did a full mechanical inspection, lubed the mag and buffer. No joy. Gas port was .094 opened it up to .125. Everything's running like a well oiled machine. Thanks to all.
     
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  12. DRZ400S

    DRZ400S Washougal, WA. Active Member

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    Sweet.
     
  13. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    AR-15 7.62x39mm Conversion
    20" rifle 7.62x39 0.120
    20" rifle 7.62x39 0.125
    16" car 7.62x39 0.078
    16" car 7.62x39 0.081
    16" car 7.62x39 0.0938
     
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