Dented case on ejection

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  • BjornF16
    Chieftain
    • Jun 2011
    • 1825

    Dented case on ejection

    Finding dents on my ejected case main body (my Satern Spartan home build, see first picture). I don't get this dent on my AA built Entry upper. The middle picture shows lack of denting on neck with my home build, while the third picture is the dented neck from AA Entry.

    What would cause the dented main body? Will this affect reloading safety?

    I am running a PRI adjustable gas block and have tuned the gas return down significantly to avoid the dented neck and increase velocity. The action cycles just fine (locks open on last round with no failure to eject/feed). I started at fully closed, then 1.5 turns open. From there I closed it another half turn (now 1 turn from fully closed). Dents occur at both settings.

    Is this possibly not enough gas to cycle carrier in time for case to clear the ejection port before being slammed to the side? The dented cases end up at the 2-3 o'clock position at half the distance of the fully gassed AA Entry (Entry brass ends up at the 4 o'clock position).


    grendel_dent1.jpggrendel_dent2.jpggrendel_dent3.jpg
    Last edited by BjornF16; 01-28-2012, 08:03 PM. Reason: Added info
    LIFE member: NRA, TSRA, SAF, GOA
    Defend the Constitution and our 2A Rights!

  • #2
    I've had the body ding on both my Grendels, but never that pronounced. I'm sure one of our resident technical guys can shed more light on causes than I.

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    • #3
      subscribing, some of my cases are dented also like that, not all though..

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      • BjornF16
        Chieftain
        • Jun 2011
        • 1825

        #4
        Update...investigating further it appears the dent is perfectly aligned with the sharp edge on the ejector port deflector (where it angles backward). So instead of flinging off violently (at full open gas) during bolt retraction and smashing the neck mid-way down the deflector, it appears the body is hitting the deflector edge during ejection.

        Maybe someone can explain this...and does it impact reloading?
        LIFE member: NRA, TSRA, SAF, GOA
        Defend the Constitution and our 2A Rights!

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        • #5
          so would putting velcro on it cure that?

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          • #6
            Velcro will soften the blow, but to fix it properly requires potty training. By this I mean fine tuning the ejector spring length. Some will cry fowl right away, and say that reducing the spring tension is just asking for reliability issues. I can tell you that I have one upper with over 14,000 rounds and no failures to eject with this adjustment. And I can also confirm the reliability fears are justified if the ejector spring is not trimmed correctly.
            The adjustment is done by grinding the spring length so that the ejector is flush with the bolt face when the spring is uncompressed. Here is a link providing further information on this adjustment. http://www.gswagner.com/arejector/arejector.html
            If you are handy, this is the route to go, if not, then stick with the velcro.
            Bob

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            • bwaites
              Moderator
              • Mar 2011
              • 4445

              #7
              What stokerj said! It's not too tough, but go very slowly and take off only a tiny bit at a time.

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              • vanguard138

                #8
                That is what solved my issue some months ago.

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                • rasp65
                  Warrior
                  • Mar 2011
                  • 660

                  #9
                  I agree with stokesrj I used the info from the link on my Grendel and a 223 AR. I made my own V-block with a piece of 2x4 and a router. Because the ejector roll pin is offset it is really hard to remove the pin without a v-block, also I bent 2 punches without it. I only pushed the roll pin out until the ejector was free because starting the offset roll pin is a PITA. You should have a spare available before you start doing this just in case. Other benefits to this are not having those deep gouges in the neck that can be seen in the 1st pic under your index finger and the brass not going as far. One other thing that may be causing this is too light a buffer but either way you will benefit from modifying the ejector spring.

                  V-Block 002.jpgV-Block 007.jpg
                  Last edited by rasp65; 01-29-2012, 02:14 PM. Reason: more info

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                  • #10
                    Originally posted by rasp65 View Post
                    You should have a spare available before you start doing this just in case.
                    [ATTACH=CONFIG]808[/ATTACH][ATTACH=CONFIG]809[/ATTACH]
                    Good point, I have multiple ejector springs and roll pins available so don't think to mention the need to have at least one spare available.
                    Bob

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                    • BjornF16
                      Chieftain
                      • Jun 2011
                      • 1825

                      #11
                      Performed the modification described in the link above...shot 5 rounds with 4 failure to extract.

                      Could it be possible that I have undergassed the system with my adjustable gas block (it is less than 1 turn from fully closed)? This gas setting worked fine prior to the modification.



                      5Feb12_Light_grendel.jpg
                      LIFE member: NRA, TSRA, SAF, GOA
                      Defend the Constitution and our 2A Rights!

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                      • rasp65
                        Warrior
                        • Mar 2011
                        • 660

                        #12
                        Bjorn The modification of the ejector shouldn't effect the extractor.

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                        • BjornF16
                          Chieftain
                          • Jun 2011
                          • 1825

                          #13
                          Sorry, let me be more precise. The case was extracted from the chamber in all cases but was not ejected properly.

                          Four shots resulted in spent case remaining loosely just above magazine. This of course interfered with insertion of next cartridge (this occurred twice). I then shot with empty magazine inserted three times. Twice the result was loose cartridge sitting on top of magazine with bolt locked back. Once the case was properly ejected.
                          LIFE member: NRA, TSRA, SAF, GOA
                          Defend the Constitution and our 2A Rights!

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                          • rasp65
                            Warrior
                            • Mar 2011
                            • 660

                            #14
                            Bjorn How much of the spring did you remove?

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                            • Drifter
                              Chieftain
                              • Mar 2011
                              • 1662

                              #15
                              Might have trimmed the ejector spring too short.
                              Drifter

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