6mm Grendel Group Design Project

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  • K_4c
    Unwashed
    • Oct 2017
    • 21

    #31
    It's not uncommon to see 6mm Grendel's driving 105 class projectiles to 2750 and 90/95 grains to 2820+ fps.

    I run the 95 tmks at 2800 FPS and I've still got 1070 ft-lb at 350 yards and 1.1 mil elevation. My 6.5 Grendel running 123 eld's at 2540 FPS, 1067 ft-lb at 350 and 1.5 mil...

    If I needed more HP, I'd grab my 6 dasher, 6xc, 7rem mag or 300 Norma.
    Last edited by K_4c; 11-21-2017, 12:26 AM.

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    • SHORT-N-SASSY
      Warrior
      • Apr 2013
      • 629

      #32
      Originally posted by bj139 View Post
      If you are punching paper at long range this looks to be a good idea but for game animals I don't know.

      Larger 6mms (243win, 6mm rem) have higher velocity to compensate for the lighter bullet. . .
      From my personal experience, I have taken Colorado Mule Deer with one-shot kills using a Remington Model 660 Carbine (20" barrel) chambered for the 6mm Remington, using Remington factory-loaded 6mm Remington Hi-Speed 100-grain Pointed Soft Point CoreLokt ammunition. Compare the downrange velocity and energy values of the 6mm AR Turbo 40 Improved, with the Sierra 110-grain HPBT Matchking projectile (BC - 0.617) (A) and the factory-loaded 6mm Remington, with the Remington 100-grain Pointed Soft Point CoreLokt projectile (BC - 0.356) (B) out to 1,000 yards, with a 10 mph crosswind, from 24" barrels:

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      • bj139
        Chieftain
        • Mar 2017
        • 1968

        #33
        SNS,
        Good chart showing there is very little difference between the 6mm Rem and 6mm AR turbo improved.

        The name "6mm AR turbo improved" is too long to be a viable cartridge.

        After buying a Howa mini Grendel, I am bitten by the 6mm bolt gun bug and am looking into aquiring one instead of more ARs..

        Comment

        • JASmith
          Chieftain
          • Sep 2014
          • 1620

          #34
          Provided the bullet impacts within its design envelope for expansion, the performance is independent of caliber for bullets of the same weight and design.

          That means we should see little difference in performance on game with 100 gr-class bullets whether we are looking at 6mm, 6.5mm or .277 mm caliber, except for how far out the bullet will still be effective. The questions of bullet weight, caliber and velocity are explored in some detail here.
          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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          • 454bore
            Warrior
            • Dec 2014
            • 111

            #35
            If you want to design a 6mm grendel that has a chance at becoming a factory round stick with the 30 degree shoulder so you don't have to do anything except a simple neck down.
            Blown out wildcats only gain around
            100 fps with a 26 inch barrel.
            Mine is 22 inch and anything longer doesn't make for a hunting rig I'd want to carry.
            What I like most about my 6mm grendel is the accuracy can be incredibly better than most calibers.
            Short fat cases with 30 degree shoulders have provided this over and over for a long time.

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            • Texas
              Chieftain
              • Jun 2016
              • 1230

              #36
              The 6mm ppc, 6mm AR, and 6mm AR Turbo have significant development history and the 6mm PPC has been tweaked for accuracy.

              Without reworking the bolt and barrel extension to allow for higher pressure it is academic
              Last edited by Texas; 11-25-2017, 02:34 AM.

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              • CavityBackBullets
                Bloodstained
                • Nov 2016
                • 98

                #37
                Originally posted by LRRPF52 View Post
                More case capacity with the optimum powder density and burn rate will result in higher mv.

                The shorter, fatter powder column in a Grendel or BR-type case will burn more efficiently than an early 1900's type 30 Remington-based case.

                It's one of the reasons you see 6.5 Grendel at lower working pressure getting the same speeds as a 6.8 case with the same bullet weight pushed to higher pressures.

                It makes no sense at all to use a lower capacity case with inferior shaping to it when we're trying to get more mv, especially with the lower bore volume of a 6mm.
                Lets just agree to disagree since I shoot them all. Do you?

                Comment

                • grayfox
                  Chieftain
                  • Jan 2017
                  • 4295

                  #38
                  This thread has been some good reading for me with lots of back and forth debate. I do have one request, could someone summarize where we stand currently with the case/chamber design for this project? If there are 2 competing, leading concepts, that's fine too - I just want to see a "score card" of the design so far that basically lets everyone know where the concept stands as of now...

                  Note, this is not to say that it's all finished design-wise (unless that is true), just a recap to say this is where it stands right now.

                  Thanks!
                  "Down the floor, out the door, Go Brandon Go!!!!!"

                  Comment

                  • StoneHendge
                    Chieftain
                    • May 2016
                    • 2009

                    #39
                    Well there could be a lucky soul out there if they haven't spent all of their Black Friday money yet. Looks like McGowen actually has a 24" 6mm Grrrr in stock and ready to ship



                    Just let me know how it shoots while I wait for mine. And if you're a lurker, create an account lol

                    Edit: wtf? Clicked link after posting to confirm it worked - looks like it has 1/2" muzzle threads?
                    Last edited by StoneHendge; 11-24-2017, 11:36 PM.
                    Let's go Brandon!

                    Comment

                    • SHORT-N-SASSY
                      Warrior
                      • Apr 2013
                      • 629

                      #40
                      Now that Hornady has finally offered our shooting world their version of the outstanding short-action 6.5mm GAP 4S SAUM long-range cartridge: the Hornady 6.5mm PRC (Precision Rifle Cartridge). I look forward to Hornady's version of the hot 6mm AR Turbo 40 Improved, for AR-15-length platforms.

                      Comment

                      • SDet
                        Bloodstained
                        • Sep 2016
                        • 82

                        #41
                        Originally posted by StoneHendge View Post
                        Well there could be a lucky soul out there if they haven't spent all of their Black Friday money yet. Looks like McGowen actually has a 24" 6mm Grrrr in stock and ready to ship



                        Just let me know how it shoots while I wait for mine. And if you're a lurker, create an account lol

                        Edit: wtf? Clicked link after posting to confirm it worked - looks like it has 1/2" muzzle threads?
                        That's fine, I'd be chopping it to 18" anyway. But it is tempting.

                        Comment

                        • LRRPF52
                          Super Moderator
                          • Sep 2014
                          • 8569

                          #42
                          Originally posted by CavityBackBullets View Post
                          Lets just agree to disagree since I shoot them all. Do you?
                          __________________________________________________ ______________________________________
                          You have an extensive working experience with 6mm wildcats between the 2 cases?

                          This one is pretty basic math.

                          We want to be able to shoot ogive lengths that can't be loaded into a 6.8 case without cutting down the case length significantly.

                          Grendel case is a neck-size operation and done without losing capacity.

                          Measure the magazine well limitations, then the bullets we want to be able to shoot.

                          Basic addition. The room isn't there for a 6.8 wildcat case to shoot 105s and 107s unless you cut the case down so far, reducing case capacity and velocity as a result.

                          6 PDK, 6mm Hagar, 6 DTI, 6x6.8, 6mm SPC, etc all don't have the ability to load 105s and 107s to mag length.

                          I just measured a 105gr Nosler RDF in a 6.8 case without moving the shoulder.

                          2.440" COL. AR15 magazine well is 2.395".

                          105gr Nosler RDF already drops into 6mm AR and 6mm AR Turbo.

                          This shouldn't be too hard to figure out.
                          NRA Basic, Pistol, Rifle, Shotgun, RSO

                          CCW, CQM, DM, Long Range Rifle Instructor

                          6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

                          www.AR15buildbox.com

                          Comment

                          • CavityBackBullets
                            Bloodstained
                            • Nov 2016
                            • 98

                            #43
                            Originally posted by LRRPF52 View Post
                            __________________________________________________ ______________________________________
                            You have an extensive working experience with 6mm wildcats between the 2 cases?

                            This one is pretty basic math.

                            We want to be able to shoot ogive lengths that can't be loaded into a 6.8 case without cutting down the case length significantly.

                            Grendel case is a neck-size operation and done without losing capacity.

                            Measure the magazine well limitations, then the bullets we want to be able to shoot.

                            Basic addition. The room isn't there for a 6.8 wildcat case to shoot 105s and 107s unless you cut the case down so far, reducing case capacity and velocity as a result.

                            6 PDK, 6mm Hagar, 6 DTI, 6x6.8, 6mm SPC, etc all don't have the ability to load 105s and 107s to mag length.

                            I just measured a 105gr Nosler RDF in a 6.8 case without moving the shoulder.

                            2.440" COL. AR15 magazine well is 2.395".

                            105gr Nosler RDF already drops into 6mm AR and 6mm AR Turbo.

                            This shouldn't be too hard to figure out.
                            Actually it can shoot 105's with enough case capacity.
                            How its accomplished though I cannot reveal.

                            Comment

                            • JASmith
                              Chieftain
                              • Sep 2014
                              • 1620

                              #44
                              Originally posted by CavityBackBullets View Post
                              Actually it can shoot 105's with enough case capacity.
                              How its accomplished though I cannot reveal.
                              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

                              • bj139
                                Chieftain
                                • Mar 2017
                                • 1968

                                #45
                                Originally posted by StoneHendge View Post
                                Well there could be a lucky soul out there if they haven't spent all of their Black Friday money yet. Looks like McGowen actually has a 24" 6mm Grrrr in stock and ready to ship



                                Just let me know how it shoots while I wait for mine. And if you're a lurker, create an account lol

                                Edit: wtf? Clicked link after posting to confirm it worked - looks like it has 1/2" muzzle threads?
                                There is a bigger selection of .223 muzzle devices with 1/2"-28 threads.
                                Clearances would have to be checked between bullet diameter and ID of muzzle device.
                                I know you know this but I am only posting this in case there are others that try it. Maybe you have more ideas.

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