please help diagnose my issue

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  • please help diagnose my issue

    I just tested a few of my first reloaded rounds and things arent looking too good. I fired 3 rounds and all of them were short stroking. My first assumption is that my loads are underpowered, however if I am not mistaken short stroking can occur with overpowered loads as well. There doesn't appear to be any other pressure signs, except for a few extractor marks on the head stamp and a few brass shavings on the bolt. I would think that if the rounds were overpowered then there would be more pressure signs, plus the extractor marks could simply be a result of the short stroking. But I need second opinions. (Wolf factory loads work fine in my gun, just saying)

    I am using the lightest load possible in my Hornady handbook. I'm using roughly 25.3gr of Benchmark powder with 100gr bullets, using Wolf brass and CCI large rifle magnum primers.

    I doubt that if I'm using the lightest load in the book that my loads are too hot, but I just want to make sure. My rifle is a CMMG 5.56 lower and a custom-made 20in upper that was originally a .223 upper. I'm sure that if it were originally designed to withstand the pressure of the .223, then it should have no problem withstanding handloads, let alone the lightest handloads in the book, which is another reason I think my loads are underpowered. Plus the buffer spring might be too stiff for these light loads, since it too was designed for the pressure of a .223.

    I also included a picture of the head stamps of the 3 rounds that I fired. Note that the one on top isn't marked as much as the other 2.

    So what do you guys think? Is it safe to increase my loads?
    Attached Files
    Last edited by Guest; 05-10-2011, 10:56 PM.
  • longdayjake

    #2
    need more powder.

    Comment


    • #3
      Originally posted by longdayjake View Post
      need more powder.
      So I should just ignore the extractor marks? I'm not an expert in this area that's why I'm asking. This is my first time reloading.

      Comment


      • #4
        I agree that you need more powder. I usually stay away from the lowest loads when starting out. I'm conservative, and you have done well to do so as well. But I think the extractor marks could be from the extractor's fit to your bolt. The primers are certainly not showing anything close to pressure problems...to whatever degree people use the primers as a pressure sign.

        I think primer flattening is only one sign. If you had some chronograph results, that would tell you a great deal. I think you need to raise the powder level a bit.

        Comment

        • Drifter
          Chieftain
          • Mar 2011
          • 1662

          #5
          Light bullets with faster powders can cause short-stroking. You might consider heavier bullets with slower powders to see if that changes anything.
          Drifter

          Comment


          • #6
            Originally posted by Drifter View Post
            Light bullets with faster powders can cause short-stroking. You might consider heavier bullets with slower powders to see if that changes anything.
            +1

            Also check to see if you're into the lands. My recent bout with short stroking came when running too much chamber pressure, not too little powder, though I have never used benchmark per se.

            Hoot

            Comment

            • longdayjake

              #7
              I think he just needs more powder. When using light bullets you want to use faster powder. The extractor marks are just a product of the softer wolf brass and a good extractor. When you start seeing some ejector marks then you know you are getting close to the limit.

              Comment


              • #8
                Early on when working with the Grendel in a rifle built by someone I don't know, I had problems with short stroking. The rifle had a 24 inch barrel, and eventually the problem was traced back to one bad gas ring. So, now whenever I have odd problems with functioning, the first thing I check is the gas system.

                Comment


                • #9
                  I tried shooting the Wolf 120gr through my rifle, and those were short stroking too. What's going on? Does Wolf use lighter loads than other available ammo? I haven't tried anything else yet. The Wolf would at least eject the brass every time, and sometimes even start to chamber the next round simply due to the friction of the bolt sitting on top of the ammo. My reloaded ammo rarely even ejected the brass. So it definitely seems like there is not enough pressure to cycle the action completely, but my question is why? Why is even the factory ammo not cycling properly? My guess is that due to the fact that my upper is custom-made from a .223 upper, it is probably designed to cycle with the higher pressures of the .223 round. Does anyone else have any opinions on this? Should I try different ammo or take my rifle to a gunsmith?

                  Comment

                  • CoolBarrelBill

                    #10
                    This was taken from Hogdens website your reloads are very light.


                    100 GR. NOS BT Hodgdon Benchmark .264" 2.200" 27.0GR 2460 36,300 PSI 29.9C GR 2739 49,900 PSI

                    Comment


                    • #11
                      So how do you explain the Wolf ammo not cycling? Bad gas ring like noone's problem?

                      Comment

                      • pinzgauer
                        Warrior
                        • Mar 2011
                        • 440

                        #12
                        Originally posted by longdayjake View Post
                        The extractor marks are just a product of the softer wolf brass and a good extractor.
                        That and the fact that the case is not held as long in the chamber due to expansion, allowing it to slide back too soon. Same for the primer, it can slide back & flatten.

                        Based on the primers my read is these are very light loads. I'd be worried about squib loads!

                        Keep in mind as you work up that extractor/ejector marks can also occur due to over gassing, especially in carbine length systems. It helps to shoot some factory to see what your rifle brass looks like with proper pressure. Then you can sort which are reload problems vs hardware problems. One of my rifles has a sharp edge on the ejector, marks all brass. Chased my tail a bit on that one.

                        Comment

                        • pinzgauer
                          Warrior
                          • Mar 2011
                          • 440

                          #13
                          Originally posted by turnbull View Post
                          I tried shooting the Wolf 120gr through my rifle, and those were short stroking too.
                          This the same rifle with the mismatched feed ramps? I'd sort that first.

                          Then look at the buffer/spring combo. Is it carbine or rifle? Does the lower work correctly with a 5.56 upper? vice versa? swap upper/lowers with a friend to try to isolate.

                          If you know it's the upper, then I'd probably start looking at the gas system. Hole blocked? Gas block installed correctly? Hole the right size?

                          No offense, but if your custom upper came with mis-matched feed ramps, I'd be worried about the rest of the basics and would be talking with the smith!

                          Lot's of things can be said about the wolf ammo, but I've not heard anyone having cycling problems.

                          Comment


                          • #14
                            Originally posted by pinzgauer View Post
                            This the same rifle with the mismatched feed ramps? I'd sort that first.

                            Then look at the buffer/spring combo. Is it carbine or rifle? Does the lower work correctly with a 5.56 upper? vice versa? swap upper/lowers with a friend to try to isolate.

                            If you know it's the upper, then I'd probably start looking at the gas system. Hole blocked? Gas block installed correctly? Hole the right size?
                            Yes, it is the same rifle. I'm not sure if this matters, but I have a 20in barrel, so its rifle-length not a carbine, but I am using an M4-style lower with the 6-position collapsible stock. The only reason I bring this up is because I've never seen a 20in AR with an M4-style stock, so I thought it possible that that combination does not work. I haven't tried my lower with a 5.56 upper.

                            I'm thinking its the gas system, because you brought up a good point about the mismatched feed ramps. I'm thinking they may have used the old .223 gas system on the rifle, which I don't think would work since the .223 operates at higher pressures. I really don't know how to check if the "hole" is the right size. Which hole? How big does it have to be? Maybe it just needs to be a bigger hole to let more gas through.

                            Comment

                            • pinzgauer
                              Warrior
                              • Mar 2011
                              • 440

                              #15
                              My understanding is that rifle uppers work ok on carbine lowers, but the opposite you can be "under buffered" due to the more violent gas action.

                              I've shot 20" rifle gas system grendel on M4 lowers with no problems. But from dialog here, most Grendels are on the high side of gassing anyway.

                              Don't know where you got the idea that .223 operates at higher pressure then Grendel, that's not my understanding.

                              I'd deal with the ramps first, as you know that's wrong.

                              But over buffering can also cause short stroking as I understand it. (But I'll defer to the input of others). I'd sure see if I could borrow a known good rifle lower to try to look for a behavior change. If it does the same with that it's almost certainly an upper problem.

                              If you have a removable gas block, You can visually inspect the port, gas tube, etc. If it's a pinned forged base, there are some things you can try. One being to use air pressure into the gas tube (gently) to blow out your gas system. You'll be able to tell if the port is unclogged.

                              There are proper sizes for the gas port. If you have a removable gas block you can determine that. If not, I'd workout the feed ramp issues first.

                              The only difference as I understand it in the Grendel vs .223 gas systems is the port size in the barrel. The gas blocks, gas tube, etc are all the same.

                              Comment

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