Weird Trouble with New Gun

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  • Retro
    Warrior
    • Jul 2016
    • 150

    Weird Trouble with New Gun

    I just finished building a new Grendel with an AA 16" barrel, Surplus Ammo and Arms billet upper, Faxon group buy bolt, Nickel Boron bolt carrier, Cerro forge 80% lower, Velocity 3* trigger, A2 stock, Odin tunable gas block with mid length gas tube. I lapped the upper and then bedded the barrel.

    Took it out to fire today and had some odd problems. First it wouldn't pick up a round from the magazine and chamber it. OK, changed out the mag. Still wasn't picking up a round. I loaded a single round and it did't want to chamber correctly, didn't want to go into battery. I kept working with it and got it to accept a few rounds and when it did it's accuracy was great. I tried it with new Hornady ELD's and my own reloads (both were 123gr). It didn't seem to matter some it would take and others it wouldn't. Then it would pick up a round or two and then jam and not go into battery. Some of the ammo got stuck in the chamber some didn't. However, none of it would fall out with just gravity.

    I brought it home and disassembled the rifle, scrubbed the chamber with a chamber brush and Hoppes, took the bolt assembly apart (nothing there), put it back together and made some dummy rounds. After repeatedly chambering and ejecting the dummy rounds it seems to be accepting the rounds better. The rounds had a COAL of 2.250 and once a bullet got stuck and I had to tap it out with a cleaning rod.

    Any advice or opinions are welcome. It's too late to make it back to the range today so I won't know if the chamber was a little tight or dirty until I can make it back to the range. I'm hoping that it will just wear in but have some doubts.
    Last edited by Retro; 04-22-2017, 12:24 AM.
  • cb4017
    Warrior
    • Dec 2016
    • 183

    #2
    I just had a similar problem. The round would be picked up from the magazine and chambered but the bolt would not go into battery. My extractor on the bolt was too tight. I removed the o-ring off the extractor spring and that fixed the problem.
    Cliff
    USN Ret., FPD Ret.

    Dues Vult

    Comment

    • pajasonc
      Warrior
      • Dec 2016
      • 203

      #3
      Originally posted by Retro View Post
      I just finished building a new Grendel with an AA 16" barrel, Surplus Ammo and Arms billet upper, Faxon group buy bolt, Nickel Boron bolt carrier, Cerro forge 80% lower, Velocity 3* trigger, A2 stock, Odin tunable gas block with mid length gas tube. I lapped the upper and then bedded the barrel.

      Took it out to fire today and had some odd problems. First it wouldn't pick up a round from the magazine and chamber it. OK, changed out the mag. Still wasn't picking up a round. I loaded a single round and it did't want to chamber correctly, didn't want to go into battery. I kept working with it and got it to accept a few rounds and when it did it's accuracy was great. I tried it with new Hornady ELD's and my own reloads (both were 123gr). It didn't seem to matter some it would take and others it wouldn't. Then it would pick up a round or two and then jam and not go into battery. Some of the ammo got stuck in the chamber some didn't. However, none of it would fall out with just gravity.

      I brought it home and disassembled the rifle, scrubbed the chamber with a chamber brush and Hoppes, took the bolt assembly apart (nothing there), put it back together and made some dummy rounds. After repeatedly chambering and ejecting the dummy rounds it seems to be accepting the rounds better. The rounds had a COAL of 2.250 and once a bullet got stuck and I had to tap it out with a cleaning rod.

      Any advice or opinions are welcome. It's too late to make it back to the range today so I won't know if the chamber was a little tight or dirty until I can make it back to the range. I'm hoping that it will just wear in but have some doubts.
      Mine is going back to AA with what appears to be a short chamber. Sounds somewhat like your issue.

      Comment

      • cb4017
        Warrior
        • Dec 2016
        • 183

        #4
        Originally posted by pajasonc View Post
        Mine is going back to AA with what appears to be a short chamber. Sounds somewhat like your issue.
        More details? Kind of sounds like you have a .125 bolt and need a .136" bolt.
        Cliff
        USN Ret., FPD Ret.

        Dues Vult

        Comment

        • A5BLASTER
          Chieftain
          • Mar 2015
          • 6192

          #5
          Cb4017, it's not the bolt, he has a faxon group buy bolt and all of those bolts are built with a bolt face depth of .136.
          Last edited by A5BLASTER; 04-22-2017, 08:10 PM.

          Comment

          • 85_Ranger4x4
            Warrior
            • Nov 2016
            • 264

            #6
            Might check and see if the mag projects enough out of the top of the magwell. Like if the mag catch is too low. Could still be mags too.

            Comment

            • A5BLASTER
              Chieftain
              • Mar 2015
              • 6192

              #7
              Also check to see if your ammo is catching the front lip of the mag body.

              Meaning cycle a few rounds by hand and see if the front edge of the case contacts the front lip of the mag body that could be causing a issue.

              Comment

              • Retro
                Warrior
                • Jul 2016
                • 150

                #8
                Nope, measured the bolt today besides, it's one of the Faxon group buy bolts. Measured .136

                Comment

                • Retro
                  Warrior
                  • Jul 2016
                  • 150

                  #9
                  I've tried that. I've polished the feed ramps, I've tried four different mags, I pulled an Odin bolt and carrier out of another rifle, I even drilled and tapped both a new cartridge and one that was fire formed to this chamber and have been working them in and out of the chamber with a cleaning rod trying to figure this out to no avail. I've thought about adding a bit of polishing compound to one of the cartridges and slightly polishing the chamber with it. I'm not a gunsmith but this also isn't my first AR build either.I sent an email to AA asking their advice on this issue. If I have to send the barrel back it's going to be a pain as I bedded the barrel with blue loctite.
                  Originally posted by A5BLASTER View Post
                  Also check to see if your ammo is catching the front lip of the mag body.

                  Meaning cycle a few rounds by hand and see if the front edge of the case contacts the front lip of the mag body that could be causing a issue.
                  Last edited by Retro; 04-23-2017, 07:20 PM.

                  Comment

                  • jurassic
                    Warrior
                    • Sep 2014
                    • 246

                    #10
                    Do you have another upper to try with that 80% lower you built? Or try the upper with a known working lower.

                    Comment

                    • 85_Ranger4x4
                      Warrior
                      • Nov 2016
                      • 264

                      #11
                      Originally posted by jurassic View Post
                      Do you have another upper to try with that 80% lower you built? Or try the upper with a known working lower.
                      Not stripping a round I agree, ruling out the lower which no offense but being an 80% off a little bit could go a long ways on locating the mag to the upper.

                      Comment

                      • Retro
                        Warrior
                        • Jul 2016
                        • 150

                        #12
                        Yep, I have both. I will try that but I have to say that the magwell on even 80% lowers are broached and I do the machine work on a Bridgeport milling machine. This is the fifth one that I have done and had no issues to date. If indeed the lower is the issue it still wouldn't explain why rounds won't chamber. The rounds just don't seem to fit the chamber correctly. I've had factory 123 Gr Hornady get stuck and the bullet ends up being pulled out of the cartridge being stuck in the lands. I've even reloaded some dummy rounds that have no primer's or powder and I've seated the bullets deeper and they still don't chamber right.
                        Originally posted by 85_Ranger4x4 View Post
                        Not stripping a round I agree, ruling out the lower which no offense but being an 80% off a little bit could go a long ways on locating the mag to the upper.

                        Comment

                        • 85_Ranger4x4
                          Warrior
                          • Nov 2016
                          • 264

                          #13
                          No, but it is hard to blame the bolt not stripping a round from the mag on the barrel though.

                          FWIW AA does seem to have a few short chamber threads recently... enough to wonder if they got a bad batch.

                          Comment

                          • Retro
                            Warrior
                            • Jul 2016
                            • 150

                            #14
                            I've been wondering about the AA barrel but I'm awaiting an answer from them on some questions that I had for them. I have two Odin barrels and have had no problems with either one of them. They are both mounted on 80% lowers and both shoot MOA to Sub MOA depending on how well I'm shooting on any particular day. I don't want to say anything about AA. If I understand correctly they contract out some of their barrels now and I wonder the same as you if they received some out of spec barrels?
                            Originally posted by 85_Ranger4x4 View Post
                            No, but it is hard to blame the bolt not stripping a round from the mag on the barrel though.

                            FWIW AA does seem to have a few short chamber threads recently... enough to wonder if they got a bad batch.

                            Comment

                            • Retro
                              Warrior
                              • Jul 2016
                              • 150

                              #15
                              I received an answer from AA first thing this morning. Here is their answer;

                              "Michael, I am aware of the posts on the Grendel forum. We have asked the moderator to advise these customers to contact us as you have done. To date you are the first person to actually send in something to us with this issue. Please be assured that we will find out what the issue is and correct if need be. Please go to our web site and complete the repair form from this link. "

                              I have been in communication with someone there via their Facebook page and am sending the barrel, BCG, and upper in for inspection and repair if they figure it's not just stupid on my part. So far, so good. AA seems to be good to go and if anyone else is having an issue with one of their barrels you need to contact them. I'm very happy with their response and time involved with communication

                              Comment

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