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    AR Feeding Issue

    I have a PSA upper mated to a KE arms lower with a PSA build kit. It functions well for many rounds, but occasionally fails to feed correctly, damaging the rounds by denting and bending them as shown below. The rounds usually make it into the chamber but don't fire because the bolt is not fully closed due to (possibly) their damaged shape. They are then hard to eject. The problem has gotten progressively worse.

    It happens almost never with ten-round P-mags, about three times with 30-round P-mags, and maybe six times with 30-round Hex mags.

    I clean it well every other time I take it to the range, and I clean the barrel and bolt every time. It's possible I'm missing some aspect of cleaning, but I doubt it.

    ​​​​It seems to perform about the same regardless of what type of ammo I use with it.

    My only three thoughts are that it might not have the right feed ramp cuts, that my buffer/spring is somehow chambering the round too fast or too slow, or that the lips/followers on all my mags are somehow being damaged.

    If you have seen this before or know what it might be, please advise me.

    IMG_20201005_2151302.jpg IMG_20201005_2151096.jpg IMG_20201005_2152017.jpg

    #2
    check the gas block
    Diplomacy is the art of saying 'Nice doggie' until you can find a rock.

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      #3
      Originally posted by Vitaman View Post
      check the gas block
      How?

      I put one together once, but I don't know what I would be checking.
      Last edited by Range Time; 10-14-2020, 12:07 PM.

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        #4
        If the BCG and upper came from PSA in the same order the feed ramps should match up.
        Giza Development: Building and Renovating Pyramids of Distinction Since 2435 BC 631-427-1691 (Beware the Sea People)

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          #5
          Originally posted by spider View Post
          If the BCG and upper came from PSA in the same order the feed ramps should match up.
          They did. Thanks.

          Comment


            #6
            Originally posted by Range Time View Post

            How?

            I put one together once, but I don't know what I would be checking.
            The gas block allen screw should be staked. if it is not, and it loosens, the gas block can shift.
            Diplomacy is the art of saying 'Nice doggie' until you can find a rock.

            Comment


              #7
              Are you using pinned 10/30 round mags? Maybe that is your issue there, possibly the pin is causing the spring and mag follower to pushup the rounds in a weird angle causing the miss feeds.

              Comment


                #8
                Originally posted by Organix View Post
                Are you using pinned 10/30 round mags? Maybe that is your issue there, possibly the pin is causing the spring and mag follower to pushup the rounds in a weird angle causing the miss feeds.
                No. I have a few 10/30 mags, but I rarely use them.

                Comment


                  #9
                  Originally posted by Vitaman View Post

                  The gas block allen screw should be staked. if it is not, and it loosens, the gas block can shift.
                  I will check that out.

                  Comment


                    #10
                    Could be undergassed. Bolt may not be cycling rearward enough. A2 style FSB, or low-pro set screw type? If the latter, check gas block for security. While not impossible, A2 style with taper pins rarely loosen. Notice any soot around the gas block/barrel interface? Leakage around where the gas tube exits the block?

                    Any chance of a rifle buffer spring by mistake?

                    Check if BCG gas key is loose, and gas key screw torque. If loose, REPLACE. I have extras.

                    Is the mag catch stud about even with the surface of the button? If not, the mags may be loose in the lower, causing a misalignment while trying to feed. Notice if it happens when it feeds from either side of the mag as opposed to the other (at about the same round count from each mag, or every other round)?

                    The way those rounds have the distortion just under the taper, they kinda look like they're being compressed. Is there an obstruction in the chamber? Carbon? Piece of broken shell casing (probably not). Just wingin' it.
                    Steve

                    Comment


                      #11
                      Where is the ejection pattern?

                      It could simply be a bad machine job by PSA- which they are known for. Perhaps its not headspaced well either.

                      Not all gas blocks need to be pinned FYI. Even BCM doesn't pin their gas blocks.

                      Comment


                        #12
                        Originally posted by -vanguard- View Post
                        Where is the ejection pattern?

                        It could simply be a bad machine job by PSA- which they are known for. Perhaps its not headspaced well either.

                        Not all gas blocks need to be pinned FYI. Even BCM doesn't pin their gas blocks.
                        It's awesome reading this when I bought a PSA upper from you!!

                        JK btw.....that thing has more than a few hundred rounds through it no problem.

                        -Vick
                        High quality building supplies since 1948! Friendly FFL transfers of long guns, receivers, and ammunition. Feel free to call us at 516 741 4466

                        Comment


                          #13
                          Originally posted by vmtcmt View Post
                          Could be undergassed. Bolt may not be cycling rearward enough. A2 style FSB, or low-pro set screw type? If the latter, check gas block for security. While not impossible, A2 style with taper pins rarely loosen. Notice any soot around the gas block/barrel interface? Leakage around where the gas tube exits the block?

                          Any chance of a rifle buffer spring by mistake?

                          Check if BCG gas key is loose, and gas key screw torque. If loose, REPLACE. I have extras.

                          Is the mag catch stud about even with the surface of the button? If not, the mags may be loose in the lower, causing a misalignment while trying to feed. Notice if it happens when it feeds from either side of the mag as opposed to the other (at about the same round count from each mag, or every other round)?

                          The way those rounds have the distortion just under the taper, they kinda look like they're being compressed. Is there an obstruction in the chamber? Carbon? Piece of broken shell casing (probably not). Just wingin' it.
                          A2. No major soot. It's a black barrel so it's not easy to see, and the little soot that comes off on a cloth could be regular soot build-up, because I never take the guard off when I clean it. Same for leakage.

                          How would I know which type of buffer it is? There are no markings other than the PSA logo. It does seem to have something loose in there, but I assume that's supposed to be like that, no?

                          BCG gas key is tight. Gas key screws tight too.

                          Interesting thought about the mag catch. Mag catch stud and surface are even, deeper if anything, but that would make it tighter, right? It does not happen every other round. The mags have some wiggle, but not a lot. no more than I would expect for empty mags. I can try with full mags.

                          The rounds are definitely being compressed. I think the bolt is slamming into them before they are in the right position, and then they are usually making it into the chamber. I don't think the chamber is obstructed, but it's kind of hard to clean in there. All I do is move the AR brush in and out and twist it a little. Then of course the swatches and bore solvent, but the .22 jag probably puts no pressure on the walls of the chamber. Do you know the "caliber" of the chamber? I could use a larger brush and jag to clean it better.

                          I did notice the bluing scraped off near the ejection port. Not sure if that's related.

                          IMG_20201014_1604507.jpg IMG_20201014_1604272.jpg
                          Last edited by Range Time; 10-14-2020, 03:17 PM.

                          Comment


                            #14
                            Originally posted by -vanguard- View Post
                            Where is the ejection pattern?

                            It could simply be a bad machine job by PSA- which they are known for. Perhaps its not headspaced well either.

                            Not all gas blocks need to be pinned FYI. Even BCM doesn't pin their gas blocks.
                            Possibly. They eject to the right, maybe a little forward.

                            Comment


                              #15
                              My guess is a feed ramp issue or typical PSA QC.

                              Comment

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