Problems with my new build - Anyone have headspace gauges?

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  • txgunner00
    Chieftain
    • Mar 2011
    • 2070
    #1

    Problems with my new build - Anyone have headspace gauges?

    My range session today with my new 12.5" build revealed some problems. I was getting heavy extractor swipe and blown primers even with the gas cut back to the point where it wouldn't fully cycle and with a H3 buffer. This was also shooting suppressed.

    Before I go and drop $60 on head space gauges, does anyone have a set I can borrow? I'll pay shipping both ways.

    I'll post more details later when I get my book in front of me but I have to leave now to take my wife on a pistol shooting / dinner date.

    I did all the trouble shooting I could do at the range including trying 3 different bolts.

    Anyone have any suggestions what else to look for?


    Some info:
    Sabre Defense 14.5 barrel shortened to 12.5
    Micro MOA switchable gas block, I'll get the port sizes later.
    FA carrier
    H3 buffer


    Bolts
    1st - AA hard use bolt
    2nd - bolt that came with my Satern
    3rd - bolt that came with the Sabre barrel. Marked "6.5 II" on one side and "X" on the other


    Got to run.......
    NRA life, GOA life, SAF, and TSRA

    "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

    George Mason, co-author, 2nd Amendment.
    Tags: None
  • BjornF16
    Chieftain
    • Jun 2011
    • 1825
    #2
    Originally posted by txgunner00 View Post
    My range session today with my new 12.5" build revealed some problems. I was getting heavy extractor swipe and blown primers even with the gas cut back to the point where it wouldn't fully cycle and with a H3 buffer. This was also shooting suppressed.

    Before I go and drop $60 on head space gauges, does anyone have a set I can borrow? I'll pay shipping both ways.

    I'll post more details later when I get my book in front of me but I have to leave now to take my wife on a pistol shooting / dinner date.

    I did all the trouble shooting I could do at the range including trying 3 different bolts.

    Anyone have any suggestions what else to look for?


    Some info:
    Sabre Defense 14.5 barrel shortened to 12.5
    Micro MOA switchable gas block, I'll get the port sizes later.
    FA carrier
    H3 buffer


    Bolts
    1st - AA hard use bolt
    2nd - bolt that came with my Satern
    3rd - bolt that came with the Sabre barrel. Marked "6.5 II" on one side and "X" on the other


    Got to run.......
    PM me...I have gauges and we're not too far apart.
    LIFE member: NRA, TSRA, SAF, GOA
    Defend the Constitution and our 2A Rights!

    Comment

    • Variable
      Chieftain
      • Mar 2011
      • 2403
      #3
      Dang Tex. That sucks! Nothing is leaping out at me right off. I'm scratching my head. Reading your combo, it should run like a champ.

      You have a heavy buffer, a heavy carrier, gas turned down, and a .308 can (extra volume, and less back pressure can-wise)..... Your Sabre barrel should have a real Grendel chamber too. Early unlock with your combo shouldn't be an issue to my thinking.

      Your gas port was set for a 14.5" barrel, but you chopped it back (less dwell), but then added a can (more dwell). The adjusted gas block should have cleaned up any difference. Something is definitely out of whack somewhere, but I can't picture it in my head yet.

      Did you try it without the can on? Anything happen then?
      Last edited by Variable; 07-13-2014, 01:41 AM.
      Life member NRA, SAF, GOA, WVSRPA (and VFW). Also member WVCDL. Join NOW!!!!!
      We either hang together on this, or we'll certainly HANG separately.....

      Comment

      • montana
        Chieftain
        • Jun 2011
        • 3209
        #4
        What ammo were you using, reloads, factory ? If your ammo is proven I would definitely look at your chamber. Short barrels in the DI gas system can sometimes create problems when suppressed. This is one of the few advantages of a gas piston over the DI. That said, I have a DI gas system with a BCM 11.5" 5.56 barrel that runs suppressed with complete reliability tuned with a Syrac adjustable gas block.

        Comment

        • molar
          Bloodstained
          • Jun 2014
          • 87
          #5
          I'm curious as to what your gas port size is.

          Don't know about Sabre grendel barrels, but their 5.56 carbine barrels are well known for having huge gas ports

          Comment

          • mongoosesnipe
            Chieftain
            • May 2012
            • 1142
            #6
            Blown primers would sujestion this is a over pressure load causing the issue,
            Punctuation is for the weak....

            Comment

            • txgunner00
              Chieftain
              • Mar 2011
              • 2070
              #7
              Originally posted by Variable View Post
              Dang Tex. That sucks! Nothing is leaping out at me right off. I'm scratching my head. Reading your combo, it should run like a champ.

              You have a heavy buffer, a heavy carrier, gas turned down, and a .308 can (extra volume, and less back pressure can-wise)..... Your Sabre barrel should have a real Grendel chamber too. Early unlock with your combo shouldn't be an issue to my thinking.

              Your gas port was set for a 14.5" barrel, but you chopped it back (less dwell), but then added a can (more dwell). The adjusted gas block should have cleaned up any difference. Something is definitely out of whack somewhere, but I can't picture it in my head yet.

              Did you try it without the can on? Anything happen then?
              I didn't this time. I actually didn't get to shoot it that much because after about the 5th shot the ejector plunger got stuck down. I spent quite a bit of time trying to get it freed up and turned out the cause was crescent shaped slivers of brass that were shaved from the case head.

              Shooting it with gas turned down resulted in less swiping but still had a few primers pop out both with FF 7.62 brass and with Hornady brass.

              All of these were mild hand loads that shoot fine in my Satern barrel. 26 grains of 8208 behind a 120 sierra SP, AK brass - 27.6 grains of 8208 behind a 123 SST, Hornady brass.

              No firing pin cratering at all. Just ejector/ extractor swiping & blown primers.

              Swapping the bolt to the 3rd one above helped with the swiping but I still had a blown primer with Hornady brass.

              More info to follow.
              Last edited by txgunner00; 07-13-2014, 07:16 PM.
              NRA life, GOA life, SAF, and TSRA

              "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

              George Mason, co-author, 2nd Amendment.

              Comment

              • txgunner00
                Chieftain
                • Mar 2011
                • 2070
                #8
                Measured the bolt face depths as best I could with my calipers.

                Satern & AA bolt - avg. .134"

                Bolt 3 - avg. .139"
                NRA life, GOA life, SAF, and TSRA

                "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                George Mason, co-author, 2nd Amendment.

                Comment

                • txgunner00
                  Chieftain
                  • Mar 2011
                  • 2070
                  #9
                  Gas port in the barrel is between .070" & .079", closer to the low end. I'm guessing .072". The large port in the adjustable gas block appears to be the same size as the barrel. The small port in the gas block is between .048" & .053".

                  edit: just checked MicoMOA's site. It appears the plate I was using has .070" & .049" ports.
                  Last edited by txgunner00; 07-13-2014, 06:38 PM.
                  NRA life, GOA life, SAF, and TSRA

                  "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                  George Mason, co-author, 2nd Amendment.

                  Comment

                  • txgunner00
                    Chieftain
                    • Mar 2011
                    • 2070
                    #10
                    I'm beginning to wonder if this barrel's chamber is out of spec. I have to seat 123 SST's back to 2.220" whereas I can seat them at mag length in my Satern (2.260").
                    NRA life, GOA life, SAF, and TSRA

                    "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                    George Mason, co-author, 2nd Amendment.

                    Comment

                    • JASmith
                      #11
                      Originally posted by txgunner00 View Post
                      I'm beginning to wonder if this barrel's chamber is out of spec. I have to seat 123 SST's back to 2.220" whereas I can seat them at mag length in my Satern (2.260").
                      This short would suggest that factory loads should get significant marks on the ogive near the next after running into battery and ejecting the unfired round.

                      If this happens or your bullet stays in the rifle, then your throat is indeed too tight or too short.

                      Comment

                      • txgunner00
                        Chieftain
                        • Mar 2011
                        • 2070
                        #12
                        That's what this is looking like. I hope it's not the case but I need to order some factory loads to test it.
                        NRA life, GOA life, SAF, and TSRA

                        "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                        George Mason, co-author, 2nd Amendment.

                        Comment

                        • Variable
                          Chieftain
                          • Mar 2011
                          • 2403
                          #13
                          Yeah, that could be bad. To my knowledge (I have no real "insider" knowledge), Sabre always used the real Grendel chamber. If you have a defective chamber that's chrome plated, well, that could be a real pain in the keester...

                          Hopefully it's something else not caught yet, and it's something easily remediable.

                          I can offer this input--- Both my 10.5" and 14.5" barrels were made by Sabre, and they run like raped apes with Wolf 120 MPT, Hornady Amax, etc... My handloads were 120 Nosler BT's seated to 2.267" with some running as long as 2.269" and they chambered fine.
                          Life member NRA, SAF, GOA, WVSRPA (and VFW). Also member WVCDL. Join NOW!!!!!
                          We either hang together on this, or we'll certainly HANG separately.....

                          Comment

                          • txgunner00
                            Chieftain
                            • Mar 2011
                            • 2070
                            #14
                            If it is defective I'm probably SOL with this barrel.
                            NRA life, GOA life, SAF, and TSRA

                            "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                            George Mason, co-author, 2nd Amendment.

                            Comment

                            • NugginFutz
                              Chieftain
                              • Aug 2013
                              • 2622
                              #15
                              Originally posted by txgunner00 View Post
                              If it is defective I'm probably SOL with this barrel.
                              Well, not necessarily. If it does prove to be short, then Mark @ PF may be able to salvage it with his patented SCS (short chamber stretcher).
                              If it's true that we are here to help others, then what exactly are the others here for?

                              Comment

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