Question about AR Upper

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  • dwhaley929

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    I just put together a 556 AR. The upper came from PSA. Rounds are not seating (at least not easily). I haven't tried to force one. They'll go farther but that shouldn't be necessary.

    Any ideas?

    Thanks
     

    Bangswitch

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    Is it catching on the feed ramp or the will the not bolt go into battery?

    If it’s catching, how are you chambering a round. Low energy feeds sometimes are met with friction from the feed ramps and mag lips causing the round to not pop-up over the ramps but dig into them. I hunt with 6.5 Grendel (that cartridge has steep shoulders) and I have dented the shoulders of the brass ‘going easy on it’.

    If it won’t chamber, may be a bad chamber, of some type of mismatch.
     

    dwhaley929

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    It's not catching on anything. It starts "sticking" and I stop pushing, not wanting to get a round stuck in there. Almost like there's cosmoline in there. I've cleaned the be-jesus out of the chamber, tried different rounds, 223, 556, etc. I've heard about break in procedures but I'm not sure what's involved in that. I don't want to just force a round home and pull the trigger. Unpleasantries may ensue.
     

    Bangswitch

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    It's not catching on anything. It starts "sticking" and I stop pushing, not wanting to get a round stuck in there. Almost like there's cosmoline in there. I've cleaned the be-jesus out of the chamber, tried different rounds, 223, 556, etc. I've heard about break in procedures but I'm not sure what's involved in that. I don't want to just force a round home and pull the trigger. Unpleasantries may ensue.

    Short chamber?
     

    bigtattoo79

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    Do you have access to a resized brass case that you could test fit so there’s no chance to set off a live round?
     

    Magdump

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    If you’ve loaded the rifle properly, lock bolt open, insert loaded mag and hit bolt release and round does not seat there’s a problem.
    Most likely a burr or the chamber needs a finish reaming. A burr inside the barrel extension can keep the bolt from locking into battery. There could also be a problem with the BCG, primarily the bolt. Check the ejector (push in with a punch to test) and extractor (pull out claw edge back and forth to check travel) and make sure the lugs are free from burrs.
    If a simple slap of the bolt release gives you good lockup and the gun will fire, run it. Break in sometimes cures a lot of minor issues.
    I’d consider a chamber needing a reamer to be a major issue on a new upper. If it looks that way, call PSA and they’ll fix you up.
     
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    geoney

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    So if you insert a a magazine, pull the charging handle fully to the rear, and allow it to go forward completely on the power of the spring, the round does not fully strip from a magazine and seat?
     

    dwhaley929

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    I got some inert test rounds to go into battery. Had to tap the bolt from underneath with a plastic punch to get them to extract at first but it's quickly getting better. At first it wouldn't seat just by releasing the bolt. Now it will. Maybe a burr or something like ya'll said.

    Thanks for the help. :)
     

    geoney

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    I got some inert test rounds to go into battery. Had to tap the bolt from underneath with a plastic punch to get them to extract at first but it's quickly getting better. At first it wouldn't seat just by releasing the bolt. Now it will. Maybe a burr or something like ya'll said.

    Thanks for the help. :)

    So if you insert a a magazine, pull the charging handle fully to the rear, and allow it to go forward completely on the power of the spring, the round does not fully strip from a magazine and seat?
     

    dwhaley929

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    So if you insert a a magazine, pull the charging handle fully to the rear, and allow it to go forward completely on the power of the spring, the round does not fully strip from a magazine and seat?

    That was the case at first. The rounds stripped from the mag fine but wouldn't fully seat even with forward assist. After working with it I've got it to where they'll seat with fairly minimum assist. I imagine that'll clear up as it breaks in. I haven't been back to the range but I'll bet it gets better as the chamber heats up.
     

    noob

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    I had a problem with an out of spec psa charging handle once that prevented it from going into battery. It didn’t feel smooth, and psa sent me a new *enhanced* one.

    I trouble shot mine by swapping parts with another rifle. Bcg worked in other rifle, which is the first thing I checked.
     

    dwhaley929

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    I had a problem with an out of spec psa charging handle once that prevented it from going into battery. It didn’t feel smooth, and psa sent me a new *enhanced* one.

    I trouble shot mine by swapping parts with another rifle. Bcg worked in other rifle, which is the first thing I checked.

    Next range trip I'll bring along a known working rifle and try swapping parts if it's still acting wonky.
     

    KDerekT83

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    bring a backpack with all your tools for completely breaking down a AR too. When I go to MCTA I usually have a fresh 80% build with me, and need to adjust/shake down the rifle. You never know what issue you're gonna run into and need to fix/adjust
     

    dwhaley929

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    bring a backpack with all your tools for completely breaking down a AR too. When I go to MCTA I usually have a fresh 80% build with me, and need to adjust/shake down the rifle. You never know what issue you're gonna run into and need to fix/adjust

    Good idea. Seems like every time I go at least one gun comes home with some sort of issue and I never have tools.
     

    DAVE_M

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    Take the carrier out, remove the cam pin and bolt. Slide the carrier into the upper and ensure that the charging handle and gas key are gliding freely over the gas tube.

    It could be as simple as a misaligned gas tube or a tight fit between the tube and gas key.
     

    dwhaley929

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    Take the carrier out, remove the cam pin and bolt. Slide the carrier into the upper and ensure that the charging handle and gas key are gliding freely over the gas tube.

    It could be as simple as a misaligned gas tube or a tight fit between the tube and gas key.

    Good to know. I'll check that. Will a misaligned gas tube show up more easily with the cam pin and bolt removed?
     

    DAVE_M

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    Good to know. I'll check that. Will a misaligned gas tube show up more easily with the cam pin and bolt removed?

    Yes, because you won't be feeling the bolt interacting with the locking lugs.

    The carrier should glide without any resistance over the gas tube. There is a tool made to adjust the tube if necessary, without harming the tube.
     
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