Inertia pulling bullet when cartridge is loaded from magazine.

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  • Inertia pulling bullet when cartridge is loaded from magazine.

    Hi guys, this is my first post but I have been reading for a couple of months off and on.

    I recently completed an 18in Grendel build and have just got around to doing some testing. Factory loads are scary accurate and I have found a reload recipe that seems promising.

    I have been reloading for almost 30 years and have come across a problem I have not encountered yet. When my reloads are slammed into battery, the inertia of the bullet causes it to slide forward in the case neck. Occasionally far enough to stick in the rifling and then pull out of the case when the round is ejected by hand.

    I have used a Hornady OAL tool and bullet comparator and am confident that the cartridges are not too long initially. I have also crimped the rounds to the point of collapsing the cartridge case and it still happens occasionally.

    I am using Hornady dies and brass and Nosler ballistic tips.

    I will be placing a call to Hornady tomorrow to ask their advice but I wanted to see if you guys have encountered the issue.

    Options that I see are:
    1. Polishing the expander button to increase bullet tension.
    2. Ordering a custom factory crimp die from Lee Precision for $30. Not sure if they can make one for the Grendel.
    3. Reducing the speed of the buffer/ spring/ bolt cycle to reduce the inertia. Not sure about the viability of this but it seems like I have seen specialized buffers and springs.

    What do you think?
  • mtn_shooter

    #2
    I'm pretty positive LEE makes the factory crimp die for the 6.5 Grendel. I originally bought a LEE die set, before my Redding set, and IIRC it has the crimp die.

    Option 1 also has some merit to it, but I would worry about concentricity.

    Comment

    • bwaites
      Moderator
      • Mar 2011
      • 4445

      #3
      Lee makes a crimp die, I have one, have never used it.

      I've not seen bullets slide forward in properly sized cases, which makes me wonder about the dies and the expander button.

      Comment


      • #4
        Originally posted by bwaites View Post
        I've not seen bullets slide forward in properly sized cases, which makes me wonder about the dies and the expander button.
        I agree, that is why I plan on calling Hornady. According to my dial caliper the expander button is exactly .264in. I know the case will spring back some but I am thinking around .260 might be better.

        Comment

        • sneaky one
          Chieftain
          • Mar 2011
          • 3077

          #5
          My forster set came with the expander ball diam. of .2655. It would barely hold a bullet! I sized a case with the center spindle assy. removed, and ended up with with the inside neck diam. of .2590-.2598. , outside was .285-.288/ Lap. brass. I polished the ball , after a light sand with # 800 sandpaper, then 1500 then 3000 grit paper., to .260. That way the dings, if any will be ironed out, without too much overworking. ( Had to do the same PLUS hone out the neck area on my first dies- LEE -- Got those to about .2580. I wanted a click more tension for hunting rounds. I dedicated 20 cases just for that .) Spin the spindle with ball on it to keep it all in line, and a little h2o, with the wet / dry s. paper. I'll be selling these to buy a Redding sizer die soon.

          Comment


          • #6
            The Redding die set I have for the Grendel has an expander ball of .262. My bullets load fine and don't move once seated. Crimping is not your solution and will only add to your problems.

            Comment


            • #7
              Just a thought,
              Remove your expander button,
              run a case thru your die,
              measure inside neck diameter,
              see if that will give more neck tension.


              Also,the hornady brass seems softer than Lapua,
              softer brass might not hold bullets as tight.
              Last edited by Guest; 07-18-2011, 01:24 AM.

              Comment


              • #8
                Originally posted by steel89 View Post
                Crimping is not your solution and will only add to your problems.
                Do you have a recommendation? Are you saying the difference is the 2 1000ths smaller your expander button is than mine?

                Comment


                • #9
                  That appears to be the obvious solution. Others may use different neck tensions, but the .262 works great for me and I think that will be a pretty cheap solution.

                  Comment

                  • Clod Stomper

                    #10
                    I know that you said that you are confident that the initial OAL is not the problem, but be sure to rule it out 100% because it is a very common problem with the Grendel. I've NEVER had such a problem with bullets sticking in the lands until I started loading this round. Try chambering rounds slowly enough that inertia will not cause the bullets to come out and see if it is still sticking. Also, when a bullet sticks in the lands and pulls out of the case, is it difficult to pull back the charging handle, or very easy? If it's easy, then it probably is a neck tension problem. If very difficult, then the bullet was probably loaded too long. I've had it happen as well.

                    Not trying to insult your experience. I've been loading for about 27 years myself and, like I said, this is the first round with which I've had this problem.

                    Just a suggestion.

                    Will

                    Comment


                    • #11
                      From Sierra.

                      Neck Tension

                      When we stop to consider the vigorous (read, downright violent) chambering cycle a loaded round endures in a Service Rifle, it becomes pretty clear it suffers abuse that would never happen in a bolt-action. This is simply the nature of the beast. It needs to be dealt with since there is no way around it.

                      There are two distinctly different forces that need to be considered: those that force the bullet deeper into the case, and those that pull it out of the case. When the round is stripped from the magazine and launched up the feed ramp, any resistance encountered by the bullet risks having it set back deeper into the case. Due to the abrupt stop the cartridge makes when the shoulder slams to a halt against the chamber, inertia dictates that the bullet will continue to move forward. This is exactly the same principle a kinetic bullet puller operates on, and it works within a chamber as well. Some years ago, we decided to examine this phenomenon more closely. During tests here at Sierra’s range, we chambered a variety of factory Match ammunition in an AR-15 rifle. This ammunition was from one of the most popular brands in use today, loaded with Sierra’s 69 grain MatchKing bullet. To conduct the test, we chambered individual rounds by inserting them into the magazines and manually releasing the bolt. We then repeated the tests by loading two rounds into the magazine, chambering and firing the first, and then extracting and measuring the second round. This eliminated any potential variation caused by the difference between a bolt that had been released from an open position (first round in the magazine) and those subsequent rounds that were chambered by the normal semi-automatic operation of the rifle. Measuring the rounds before chambering and then re-measuring after they were carefully extracted resulted in an average increase of three thousandths (0.003") of forward bullet movement. Some individual rounds showed up to seven thousandths (0.007") movement. Please bear in mind that these results were with factory ammunition, normally having a higher bullet pull than handloaded ammunition.

                      To counteract this tendency, the semi-auto shooter is left with basically two options: applying a crimp or increasing neck tension.


                      Article

                      Comment


                      • #12
                        Gswamp,
                        If you put 'Crimp' in the search box it will give you alot of previous discussions covered in the forum. There are quite a few competition shooters here in the forum (I'm not one of them) who are keenly aware of the issues with crimping. A very light taper crimp isn't too bad but most of the Grendle bullets aren't designed to be crimped. Here is one of the discussions I found to be a good read.
                        Should I be crimping? I would guess that with most loads, the case is full and there won't be much if any rooom for set back. Light taper or none at all? TIA

                        Comment


                        • #13
                          Thanks for all of the responses guys.

                          I think the solution is obvious, I need more neck tension.

                          I even tried maxscm's suggestion of sizing without the expander button. I did a couple and loaded them again and again without any bullet movement. I will polish my expander button down to .260. If that does not solve it I will pick up a .257 button to try.

                          Here is a pick of the Grendel:



                          Thanks again

                          Comment


                          • #14
                            First what upper are you running, AA or other, SLOAN.....

                            Comment


                            • #15
                              Specs are here

                              Finished this a month or so ago. Here are the specs: Lower: Wilson Combat Tactical Custom lower receiver. Doublestar lower parts kit. Bill Springfield four pound trigger. DPMS receiver extension tube, spring and buffer. Magpul MOE collapsable butt stock. Flat dark earth. Magpul enhanced rubber butt pad. Magpul MOE grip.

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