New build, failure to extract spent shell, charging handle hard to pull back

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  • Ateup
    Bloodstained
    • Dec 2016
    • 25

    New build, failure to extract spent shell, charging handle hard to pull back

    Ok, need a little help. Built my grendel from ground up. First time out to test fire and had failure to extract, charging handle very hard to pull back. 3 rounds and I aborted effort. Research lead me to think it was an undergas issue and case was swelling causing it to be stuck in chamber. Bought gas block alignment tool and reinstalled my Jp adjustable gas block and found that it was slightly off so thought that was problem. Headed to range today with adjustment screw on block out 1 turn. Same issue. Took another turn out of screw and same issue. After 1st FTE episode I removed firing pin at home and was able to manually charge and eject live rounds no problem. Any ideas? Thanks in advance.

    20" odin barrel
    JP bolt
    Fail zero BC
    hornady black ammo
  • Rickc
    Warrior
    • Aug 2016
    • 311

    #2
    For some reason it is a common problem with the grendel. Happened to me. After you run 20 rounds through it.problem will go away.

    Open that gas block all the way, Lubricate the hell out of your bolt carrier and shoot.it.

    Easiest way i found to unjam it was to separate the upper.and.lower and tap on the bolt carrier inside the upper.

    Comment

    • Klem
      Chieftain
      • Aug 2013
      • 3507

      #3
      Originally posted by Rickc View Post
      For some reason it is a common problem with the grendel. Happened to me. After you run 20 rounds through it.problem will go away.

      It is not a common problem with the Grendel.

      There will be some technical issue common to both of you, but there's no evidence it is common. Or peculiar to just this calibre.

      Comment

      • Rickc
        Warrior
        • Aug 2016
        • 311

        #4
        Well do a little search on this forum. Failure to extract.

        But it is easy to fix. Use an adjustable gas block and open it wide open, lubricate the hell out of the bolt carrier on break in and shoot the hell out of it. I reccomend factory ammo on break in. Eliminates one variable

        If you follow most of these threads the gun just magically begins to cycle properly.

        Comment

        • rabiddawg
          Chieftain
          • Feb 2013
          • 1664

          #5
          I agree with klem. It's not an inherent problem with the round. All mine are built by Alexander arms or Precision Firearms and they ran from the start. A properly machined and assembled Grendel is no more likely to fail than any other.
          Knowing everthing isnt as important as knowing where to find it.

          Mark Twain

          http://www.65grendel.com/forum/showt...2-Yd-Whitetail

          Comment

          • Bigs28
            Chieftain
            • Feb 2016
            • 1786

            #6
            Originally posted by Ateup View Post
            Headed to range today with adjustment screw on block out 1 turn. Same issue. Took another turn out of screw and same issue.


            hornady black ammo
            First do you have the detent model gas block or the adjustment screw with locking set screw?

            When you say you backed it out 1 turn, did you mean a full 360 or just 1 click of the detent? Straight from jp on using detent model.

            2. Back the adjustment screw out one full rotation (six clicks). Load a single round into the
            magazine, chamber it, and fire. If the bolt doesn’t open at all, open it another four clicks and
            try again. Most likely, the bolt will short stroke at this setting. If that is the case, clear the
            rifle before proceeding.

            I feel you are not opening it enough and still undergassed.

            Comment

            • A5BLASTER
              Chieftain
              • Mar 2015
              • 6192

              #7
              I agree with Bigs28, your gas block is closed off to much open it up a good bit more and retry.

              Mine did the same thing when I first put it together and that was my problem, my barrel uses rifle length gas just like yours and I use the JP gas block as well and I had to start the block at half open, if I started lower then half open it would do the same thing you said yours did.

              What model of JP gas block do you have?

              Comment

              • VASCAR2
                Chieftain
                • Mar 2011
                • 6219

                #8
                Some barrel manufactures don't drill the appropriate size gas port hole. There have been barrels sold with under size gas ports and many with over size gas ports. It can be difficult to tell the difference between under gassed and over gassed system on a new build.

                It always helps to identify the barrel length, and gas system (ie, pistol, carbine , midlength, intermediate or rifle length). Manufacture of the barrel, whether Stainless Steel or CMV with type of rifling and twist doesn't hurt either as some brands are known to have issues. It's a good idea to measure the gas port diameter on a troublesome build that way it is easier to help diagnose the problem.

                Comment

                • LRRPF52
                  Super Moderator
                  • Sep 2014
                  • 8569

                  #9
                  Originally posted by Rickc View Post
                  For some reason it is a common problem with the grendel. Happened to me. After you run 20 rounds through it.problem will go away.

                  Open that gas block all the way, Lubricate the hell out of your bolt carrier and shoot.it.

                  Easiest way i found to unjam it was to separate the upper.and.lower and tap on the bolt carrier inside the upper.
                  I've lost count on how many 6.5 Grendels/uppers I have built now.

                  I don't know what I'm doing wrong, but they all just seem to work right out of the gate, like all my other AR15 builds.

                  I just haven't seen FTExtract that I can recall, come to think of it. Could be my memory going to crap too though, so who knows...

                  OP: What's your buffer and recoil spring set-up?

                  What's your gas port diameter?

                  A 20" should have a RLGS and a .094" port.

                  When you say "out 1 turn" on the Adjustable Gas Block, does that mean 1 turn from closed? Is so, there's your problem-nowhere near enough gas. Keep opening it until you get lock back on the magazine, then open it another half turn or more, considering weather conditions and their effects on the gas system when they get warmer or colder. Colder will require more gas, hot will require less.
                  NRA Basic, Pistol, Rifle, Shotgun, RSO

                  CCW, CQM, DM, Long Range Rifle Instructor

                  6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

                  www.AR15buildbox.com

                  Comment

                  • Ateup
                    Bloodstained
                    • Dec 2016
                    • 25

                    #10
                    Thanks everyone for replying. I just tested the gas tube flow by tying a baggie over end of my muzzle and putting a spent casing in the chamber and attached a small tube to end of gas tube in the upper. Flow at 2 full turns out from closed (adjustment screw does not click) did seem restricted. Made one more full turn out and it seems to flow much better. Going to head to range asap to give it another go.

                    BTW: I do not know what the gas hole in the barrel (20" odin stainless) is sized and the gas tube is rifle length. AR stoner rifle buffer with JP tuned and polished buffer spring. Jp gas block is the model with the set screw in front and side adjustment screw. 4 barrel clamp screws at bottom.
                    Last edited by Ateup; 04-06-2017, 02:07 AM.

                    Comment

                    • Lastrites
                      Warrior
                      • Apr 2017
                      • 678

                      #11
                      Originally posted by Ateup View Post
                      After 1st FTE episode I removed firing pin at home and was able to manually charge and eject live rounds no problem. Any ideas? Thanks in advance.
                      Call yourself Lucky, one should never remove the firing pin and then proceed to start racking an AR. Luckily the cam pin didn't turn on you and cause one of the worst jams of the carrier you would likely ever experience. Word of advise, don't try that again or you will be back asking how to get it unstuck.

                      The above is a mute point if you did remove the cam, but you didn't mention that you had so I thought I would share.

                      Comment

                      • Ateup
                        Bloodstained
                        • Dec 2016
                        • 25

                        #12
                        Originally posted by Lastrites View Post
                        Call yourself Lucky, one should never remove the firing pin and then proceed to start racking an AR. Luckily the cam pin didn't turn on you and cause one of the worst jams of the carrier you would likely ever experience. Word of advise, don't try that again or you will be back asking how to get it unstuck.

                        The above is a mute point if you did remove the cam, but you didn't mention that you had so I thought I would share.
                        Don't remember if I removed it or not but thanks for the advice. Makes sense.

                        Comment

                        • AZBackcountry
                          Bloodstained
                          • Nov 2016
                          • 78

                          #13
                          If you're still having problems ejecting after proving the gas tube/block aren't the issue look at your bass. Look for scratches. Run a caliper up and down the sides of the brass looking for bulges, bumps, rings or egg shapes. There will be ejector pings at the top of the neck and are normal. It could be a chamber flaw since unfired rounds cycle easily. And "charging handle very hard to pull back".
                          Life is fun when your ammo budget is more than your house payment.

                          Comment

                          • Texas
                            Chieftain
                            • Jun 2016
                            • 1230

                            #14
                            Originally posted by LRRPF52 View Post
                            I've lost count on how many 6.5 Grendels/uppers I have built now.

                            I don't know what I'm doing wrong, but they all just seem to work right out of the gate, like all my other AR15 builds.

                            I just haven't seen FTExtract that I can recall, come to think of it. Could be my memory going to crap too though, so who knows...

                            OP: What's your buffer and recoil spring set-up?

                            What's your gas port diameter?

                            A 20" should have a RLGS and a .094" port.

                            When you say "out 1 turn" on the Adjustable Gas Block, does that mean 1 turn from closed? Is so, there's your problem-nowhere near enough gas. Keep opening it until you get lock back on the magazine, then open it another half turn or more, considering weather conditions and their effects on the gas system when they get warmer or colder. Colder will require more gas, hot will require less.
                            I have built nine 6.5 Grendels in the past three months and they all have functioned well from the start. It does sound like you are under-gased, and I would agree that you need to open up the gas block, and if that doesn't work, recheck the gas port alignment.

                            Comment

                            • Texas
                              Chieftain
                              • Jun 2016
                              • 1230

                              #15
                              Originally posted by Lastrites View Post
                              Call yourself Lucky, one should never remove the firing pin and then proceed to start racking an AR. Luckily the cam pin didn't turn on you and cause one of the worst jams of the carrier you would likely ever experience. Word of advise, don't try that again or you will be back asking how to get it unstuck.

                              The above is a mute point if you did remove the cam, but you didn't mention that you had so I thought I would share.
                              I have a couple of "show pins" left over from when we use to display the rifles, and we ground the end of the firing pin so that it would not protrude through the bolt. If they were not in the bolt, someone would check the weapon and it would lock up -- food for thought.

                              Comment

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