6.5 Grendel Max

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  • s3silver
    Warrior
    • Sep 2014
    • 277

    6.5 Grendel Max

    I was browsing the net and came across this forum. 6.5 grendel with shoulder blown forward. Anyone else done this? Seems interesting in a bolt gun setup.


    I had a hankering for a micro action chambered for something that would be a little more than the usual suspects and had been increasingly interested in the 6.5 Grendel but thought that there was still a little left on the table as far as capabilities went with the Grendel cartridg...
  • JASmith
    Chieftain
    • Sep 2014
    • 1620

    #2
    Von Gruff developed a cartridge with that Nickname and shared with us both the development of the wildcat and a bullet mould to go with it. The first thread is http://www.65grendel.com/forum/showt...ht=Grendel+Max.

    He had reamers and mould built, the posted who he got tuhem from so others could try the cartridge too.
    shootersnotes.com

    "To those who have fought and almost died for it, freedom has a flavor the protected will never know."
    -- Author Unknown

    "If at first you do succeed, try not to look astonished!" -- Milton Berle

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    • sneaky one
      Chieftain
      • Mar 2011
      • 3077

      #3
      S3S--- it is a cool bolt gun round. I'm working on an AR version- about a 75% gain as to the bolt gun gain. I'll have more data this spring.

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      • s3silver
        Warrior
        • Sep 2014
        • 277

        #4
        JAS - thanks for the link. Very good and interesting read.


        Sneaky - an ar version sounds even cooler. Can wait to see your results.


        Grendel is such an efficient and accurate round.

        Comment

        • Drift
          Warrior
          • Nov 2014
          • 509

          #5
          Would someone please remind me. If I get a Grendel rechambered into a Grendel Max and then shoot regular factory ammo out of that, "How much velocity can I expect to loose compared to a standard Grendel?"

          Comment

          • Drillboss
            Warrior
            • Jan 2015
            • 894

            #6
            Nope, the Grendel Max chamber won't fire factory Grendel ammo. He's blown the shoulder forward such that the headspace won't allow the shorter SAAMI cartridge.

            Comment

            • sneaky one
              Chieftain
              • Mar 2011
              • 3077

              #7
              Drill, it will fire, and fireform the rounds in the Max chamber. The bolt lugs hold the round in place. Von Gruff & I talked about this as he asked for my input, and a few others-- to get the reamer print done. 3 years ago...


              He used Factory Hornady cases to fireform to the Max. case. So it's a duh, on that . I have done a many here in testing also.

              Revisit the Max- reamer print- - it's reamed .050 longer

              He sent me a dozen retired Max cases , from NZ- for me to measure upon. It's my goal to make a Max lite version for AR's.
              Last edited by sneaky one; 02-09-2017, 02:17 AM.

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              • s3silver
                Warrior
                • Sep 2014
                • 277

                #8
                That's what I thought from the read. He used factory cases to fireform since it was the same grendel specs, just .050 longer.

                Sneaky - can't wait to see your results. What's your timeline?

                Comment

                • Drillboss
                  Warrior
                  • Jan 2015
                  • 894

                  #9
                  I stand corrected. My answer was based on what Von Gruff told me once:

                  Giday Drillbos and no the factory ammo cant because of the headspace which is .050 longer with the GM. I did get a couple of boxes of Hornady ammo when I first built the rifle more to get the brass than anything else and debulleted, saved the powder in another set of cases, expanded the neck to 30 cal then necked back down in the Grendel dies with a .05 spacer glued to the shell holder which is a permanent fixture that stays with the Grendel dies. This is how all reloading is done but for the first necking down I added a .006 shim to give me a crush fit in the chamber, added the powder backinto the cases and seated the same bullet to an OAL of 2.405. The GM case gives me a near 10% case capacity advantage but with the bullet seated long it opens up more space for the powder so that with 32.6gn CFE223 under the 123gn bullet I get 2700fps from my 21 in barrel and at just 53K psi. The 100gn ttsx gets 2950 but the 123gn has a better long range performance with less elevation and windage drift.
                  Without a doubt the most efficient and usable rifle I have built (other than a little 20 VarTarg that is)

                  Comment

                  • Rickc
                    Warrior
                    • Aug 2016
                    • 311

                    #10
                    Wonder what the velocity gain would be with an ackley improved grendel

                    My 6mm turbo 40 has a blown out shoulder of 40 degrees and a much shorter neck than the original grendel case

                    Suprised someone hasn't already done it

                    Comment

                    • ricsmall
                      Warrior
                      • Sep 2014
                      • 987

                      #11
                      Originally posted by Rickc View Post
                      Wonder what the velocity gain would be with an ackley improved grendel

                      My 6mm turbo 40 has a blown out shoulder of 40 degrees and a much shorter neck than the original grendel case

                      Suprised someone hasn't already done it
                      I've thought on it some!! Lol. I love an AI cartridge. I don't think the factory ammo will fire in the max chamber. Seems to me gruff was necking up then back down to 6.5 leaving .050" of neck to act as a false shoulder.

                      Richard
                      Member since 2011, data lost in last hack attack

                      Comment

                      • JASmith
                        Chieftain
                        • Sep 2014
                        • 1620

                        #12
                        Originally posted by Rickc View Post
                        Wonder what the velocity gain would be with an ackley improved grendel

                        My 6mm turbo 40 has a blown out shoulder of 40 degrees and a much shorter neck than the original grendel case

                        Suprised someone hasn't already done it
                        Run, or get a buddy to run, the 6.5 Grendel with a powder like H335 in QuickLoad. Do this at the suggested 50ksi for AR bolt happiness, then repeat at the pressure YOU THINK might be OK for your rifle.

                        Then, morph the Grendel case into the configuration you are thinking about and repeat with the same. Pressure levels and powder.

                        You will have four muzzle velocities to plug into your favorite exterior ballistics calculator.

                        Do this and see what the cihange in wind drift at the ranges you are interested in. Is the gain more or less than 1 moa? 1/2 moa? Or 1/4 moa?

                        The answer combined with how well you believe you can shoot will tell you whether the exercise is worth the bother.

                        I have done exercises similar to this for a couple of wildcats and haven't yet convinced myself that the blown forward, blown out, higher pressure combiniation will make a real difference in my ability to hit at range.

                        Nonetheless, like any choice of cartridge, rifle, or bff, the resulting state of mind may be enough. Most of us will not criticize your chosen path if for no other reason than curosity to see how it works out!

                        VonGruff has done us a real favor by already having done the experiment. It definitely seems to have worked well for him and we learned a bit too.
                        Last edited by JASmith; 02-09-2017, 06:37 PM.
                        shootersnotes.com

                        "To those who have fought and almost died for it, freedom has a flavor the protected will never know."
                        -- Author Unknown

                        "If at first you do succeed, try not to look astonished!" -- Milton Berle

                        Comment

                        • D.Davis
                          Warrior
                          • Sep 2013
                          • 150

                          #13
                          I shoot a 20 Grendel AI in a CZ 527. I like it in a bolt gun, but for feeding reasons in a semi I think the shoulder angle should be left alone. Dave.

                          Comment

                          • sneaky one
                            Chieftain
                            • Mar 2011
                            • 3077

                            #14
                            S3--- Von and I went around a bit on the AI- I wanted it- he strongly recommended against it.

                            Timeline will be spring this year- a few more numbers to go through, Need to check the viability of this project again. I gained plenty of deer harvesting usage, by going lighter in all copper pill wts., to get my dream gun done, in std. Grrr trim- chambers with awesome results.

                            Maybe Jasmith can email me a reason to skip the idea...

                            Joe Joe,,,?

                            Comment

                            • Rickc
                              Warrior
                              • Aug 2016
                              • 311

                              #15
                              Originally posted by D.Davis View Post
                              I shoot a 20 Grendel AI in a CZ 527. I like it in a bolt gun, but for feeding reasons in a semi I think the shoulder angle should be left alone. Dave.
                              I have the turbo 40 improved. It feeds flawlessly

                              See pic below beside its parent case the 6.5 grendel. There is 1 gr of h20 capacity gain between the grendel and the Ackley Improved. Does that equate to 100 to 150 fps velocity increase with the 123's?

                              [IMG][/IMG]

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