Why? Why? Why? I Wanna Cry

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  • jayson9930
    Unwashed
    • Mar 2017
    • 8

    Why? Why? Why? I Wanna Cry

    So Ladies and Gentlemen. First Grendel Build
    Aero upper ( lapped)
    Aero lower
    Aero carrier
    BA Grendel Bolt
    BA Hanson Grendel barrel 20" RL ( bedded)
    SLR 7 series adjustable gas block with RL gas tube
    SLR 16.5 solo lite handguard
    Geissele SSE Trigger
    Geissele Airborne Charging Handle
    Magpul 2.0 UBR Gen 2
    JP SCS gen 2 standard
    Elander mags
    VG6 762 Gamma

    First trip to the range seems the rifle was short cycling. Bolt not locking back and brass not being released from the extractor. Case neck would get pinned against front ejection port, even with the gas block fully open. Using PPU 120 gn. With Hornady SST and Amax 123 gn.Bolt would not lock back, but would eject the brass. On all the rims brass you can clearly see and feel marks from the extractor. Packed up went home back to the drawing board. Researching the Hoard for help with isolating the problem. Double checking everything twice. Second trip to the range with extra bolt carrier, my A1 complete rifle length lower and a standard carbine buffer and spring set. Installed standard carbine buffer and spring and started with PPU 120 gn. Got it to lock back, but the bolt stayed In battery and the brass was still lodged in the extractor SLR gas block between 11-15. Swapped Aero carrier with BCM carrier, PPU again. Got the bolt to lock back completely, but brass still not being released from the extractor. Hornady SST and Amax 123 gn a different story. Seems to be cycling fine. Although it will still leave brass bites on the rim. Reinstalled JP SCS and is still cycling fine with the Hornady at setting 12 on the gas block. A1 complete rifle length. Bolt locks back PPU 120gn still will not release from extractor. Hornady cycling fine though rifle lower still leaving bites on the brass. So why am I crying? I think I'm pretty close to having my first Grendel build. Pretty emotional, lol. I would appreciate some input and so help on the following . Why the hard bite marks on the brass ? Why am I having trouble with the PPU 120 gn not cycling. Why the Aero carrier would not lock back? Could it been that simple, or is there something I'm missing? Recommendations on a reliable carrier? My BCM is a complete back up BCG in kit. Hopefully I will continue to cry tears of joy.
  • VASCAR2
    Chieftain
    • Mar 2011
    • 6219

    #2
    I'd make sure BA did not use a 5.56/223 extractor. If you got the proper 6.5 Grendel extractor check to see if it is smooth. If there is an O ring on the extractor spring, try removing it. Over gassed and under gassed can be confused as they can exhibit the same malfunctions. In a rifle tube I would not use a carbine spring and carbine buffer. In a rifle buffer tube you need a rifle spring and rifle buffer or a properly weighted SCS.

    While your looking at your bolt examine the ejector, it helps to radius the sharp edge off the end of the ejector. This allows the larger diameter case to to feed onto the face of the bolt.

    Not all bolt carriers are the same weight, an M-16 carrier will be heavier than a non full auto carrier. The PPU ammo was recalled and even the Wolf Gold 120 grain MPT had some inconsistent lots. I wouldn't judge your builds reliability totally on the PPU ammo.

    Are you liberally lubing the bolt and carrier prior to shooting. While trying to diagnose you cycling problems I'd only load two or three rounds in the mag. A new fully loaded mag puts a lot of drag on the bottom of the bolt carrier. On a new buld where everything is very tight this can be the difference between good cycle or a jam.

    Did you bed the gas block with loctite, sounds like your loosing gas pressue. Ensure the bolt carrier is not loosing gas around the key. If the gas block is out of alignment to far forward or aft or to the side you can experience these problems. There should be carbon around the gas block if it is loosing gas pressure.
    Last edited by VASCAR2; 07-16-2017, 12:25 PM.

    Comment

    • Rockfish Dave
      Bloodstained
      • Feb 2016
      • 34

      #3
      Did you start with the gas block fully closed and slowly open, one click at a time?

      My mid length has similar symtoms when over gassed.

      My PPU ran good most of the time, but the last mag I ran went from under pressure to HOT in 4 rounds. So bad I'm going to pull the remainder down and reload. I retro spect the money would have been better spent on Lapua brass and loaded my self. I can't stand factory ammo.
      Last edited by Rockfish Dave; 07-16-2017, 12:42 PM.

      Comment

      • StoneHendge
        Chieftain
        • May 2016
        • 2009

        #4
        You are using the buffer tube spacer with the SCS in a rifle tube, right?

        I have had an out of spec carrier from one of the big pricy names I picked up on sale. Too much friction to allow it to cycle properly. Had me banging my head against the wall. I'm a self admitted Aero FanBoy, but unfortunately their customer service system is an absolute hell hole
        Let's go Brandon!

        Comment

        • jayson9930
          Unwashed
          • Mar 2017
          • 8

          #5
          I actually went in reverse. Highest to the to lowest that it stopped cycling with the Hornady. On my first trip the first couple of settings brass got stuck in the chamber and wouldn't unlock. Had to play carpenter and pound it out. Didn't know there was a recall on PPU. May just do the same and pull them. Have some new brass from AA. Gathering supplies and info for reloading the Grendel as we speak.

          Comment

          • jayson9930
            Unwashed
            • Mar 2017
            • 8

            #6
            I actually used my complete Colt M16A1 lower from a retro build. It's already fitted with a rifle length stock, spring and buffer. For trouble shooting purposes. I'm actually running a gen 2.0 Magpul UBR that's an adjustable/ collapsible carbine stock. Same, same got the Aero BCG on sale. Hopefully I don't get the run around. Had a problem with a Spike's NIB in the past. No questions asked, received an apology and replacement. Guess I'm gonna pony up again for another BCM.

            Comment

            • 204 AR
              Warrior
              • Sep 2015
              • 239

              #7
              Did you de-horn the extractor? The sharp corners need rounded or beveled off.

              Comment

              • jayson9930
                Unwashed
                • Mar 2017
                • 8

                #8
                No I haven't, will do that thanks for the advice my friend.

                Comment

                • Lastrites
                  Warrior
                  • Apr 2017
                  • 678

                  #9
                  Have air compressor? If yes pressure test the bcg key and the barrel/gas block and check for leaks.

                  Comment

                  • Jakegsxr11
                    Warrior
                    • Nov 2016
                    • 114

                    #10
                    I also had to polish my group buy extractor or casings would stick in the chamber. It functioned perfectly after a light polish.

                    Comment

                    • jayson9930
                      Unwashed
                      • Mar 2017
                      • 8

                      #11
                      How did you go about the polishing?

                      Comment

                      • BluntForceTrauma
                        Administrator
                        • Feb 2011
                        • 3897

                        #12
                        Originally posted by 204 AR View Post
                        Did you de-horn the extractor? The sharp corners need rounded or beveled off.
                        This gets my vote, too. If not handy with the tools, maybe swap in a couple other extractors known to work?
                        :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

                        :: I Drank the Water :: Revelation 21:6 ::

                        Comment

                        • bj139
                          Chieftain
                          • Mar 2017
                          • 1968

                          #13
                          I think shooting the Wolf steel case ammo removes the sharp corners on the extractor. Steel on steel.

                          Comment

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