6mm Grendel Group Design Project

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  • StoneHendge
    Chieftain
    • May 2016
    • 2009

    #46
    Originally posted by bj139 View Post
    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.
    Let's go Brandon!

    Comment

    • bj139
      Chieftain
      • Mar 2017
      • 1968

      #47
      A2 flash hider would work just fine. Just look at the muzzle of your 5.56.
      There is plenty of clearance. 0.01" additional each side of center.
      Last edited by bj139; 12-04-2017, 04:35 PM.

      Comment

      • Bwild97
        Warrior
        • Jan 2015
        • 217

        #48
        Why the .243" and not a .257" ?

        In the quest for MV and BC, what are we loosing in hunting capability? Are sectional densities equal in 6mm and 6.5mm?

        I thought the 6.5 Grendel already provided the optimal balance between target shooting and hunting performance.

        Comment

        • bj139
          Chieftain
          • Mar 2017
          • 1968

          #49
          Originally posted by Bwild97 View Post
          Why the .243" and not a .257" ?

          In the quest for MV and BC, what are we loosing in hunting capability? Are sectional densities equal in 6mm and 6.5mm?

          I thought the 6.5 Grendel already provided the optimal balance between target shooting and hunting performance.
          That was my original question as well.

          The 6.5mm (.264") is midway between the beloved 30 cals for us old timers and the newbies 5.56mm.

          It is just the ideal compromise.

          Target shooters are looking for the last tiny advantage so the 6mm has value to them.

          Comment

          • StoneHendge
            Chieftain
            • May 2016
            • 2009

            #50
            Originally posted by bj139 View Post
            Just look at the muzzle of your 5.56.
            Lol - my "new" 20" target 556 (ie, life after 22 Nosler) has a VG6 Epsilon on it - has about as much muzzle movement and recoil as a 22lr.

            But for target, 6mm offers more than a "last tiny advantage." I'm pretty confident that my 26" 6mm Grrr barrel arriving today (yay!) will have ballistics nipping at the heels of what I do with 130's in my 6.5 S'more. To put it in perspective, I was having a lot of fun with a buddy yesterday shooting 1k in winds that ranged from the high teens to the high 20s. Drop and 20 mph wind drift were 24' and 8.5' with me S'more while drop and 20 mph wind drift were 29' and 11' in my 22" 6.5 Grendel shooting 123 gr Scenars. The S'more got more first shot hits, while follow up shots were faster with the Grendel due to lower recoil. That didn't equate into more second shot hits with the Grendel since it is more susceptible to wind speed fluctuation. But with 6mm Grrr, you would have the S'more 1st shot hit percentage combined with even lower recoil than 6.5 Grrr. At one point when I was on the Grendel, the wind got into the high 20s and my horizontal hold was 5 mils on a 16" (half mil) target - over 15' of wind drift. Was kind of crazy to dial the scope back to zero at the end of the day and take a look at what the crosshairs were actually pointing at with a 9.1 mil vertical and 5 mil horizontal hold

            Bwild, I don't know if anyone even makes a .257 match target bullet. My interest in 6mm Grrrr is solely on the basis of target shooting, with the caveat that I consider p-dogs to be exploding targets.
            Let's go Brandon!

            Comment

            • bj139
              Chieftain
              • Mar 2017
              • 1968

              #51
              I think most of us here only have a pipe dream of shooting at 1000 yds. As in precision match grade pipe.

              My home range only has 100 yds maximum, so I am resigned to the pursuit of sub MOA groups.

              Isn't the last tiny bit your difference of 1 foot in hold left between 6mm and 6.5mm?

              Just like the last tiny bit of shooting a 0.4 MOA group vs. a 0.6 MOA group.

              Comment

              • LRRPF52
                Super Moderator
                • Sep 2014
                • 8569

                #52
                Originally posted by Bwild97 View Post
                Why the .243" and not a .257" ?

                In the quest for MV and BC, what are we loosing in hunting capability? Are sectional densities equal in 6mm and 6.5mm?

                I thought the 6.5 Grendel already provided the optimal balance between target shooting and hunting performance.
                Good to see you again!

                If we're limited to the AR15 magazine well dimensions, then .257" is really close to 6.5mm, suffers from a lot of the same challenges, but I'm a big fan of the .257 bore.

                It has been neglected when it comes to bullet selection, but I really think is a great balancing point if we could get bullet manufacturers to support it.

                I think this will actually happen moving forward, as Hornady has already done some work on the .257 Creedmoor. .257 Creedmoor was featured in a recent Handloader Magazine as well.

                For competitive shooters in long range matches, most people want a .550 to .6 or higher G1, .275 to .3 + G7 bullet. That's easier to do in .257 and keep the recoil down than it is in 6.5mm (140gr + cup and core).

                In a 6mm, that usually puts you in the 105gr + weight category.

                It could be done in .257 with a 123gr - 130gr, but would be quite long for the AR15.
                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

                • JASmith
                  Chieftain
                  • Sep 2014
                  • 1620

                  #53
                  Originally posted by Bwild97 View Post
                  Why the .243" and not a .257" ?

                  In the quest for MV and BC, what are we loosing in hunting capability? Are sectional densities equal in 6mm and 6.5mm?

                  I thought the 6.5 Grendel already provided the optimal balance between target shooting and hunting performance.
                  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

                    #54
                    People complain about lighter bullets having less ringability on steel targets.

                    Doesn't the 6mm give up ringability for the sake of better ballistics?

                    Comment

                    • BluntForceTrauma
                      Administrator
                      • Feb 2011
                      • 3897

                      #55
                      Originally posted by bj139 View Post
                      The 6.5mm (.264") is midway between the beloved 30 cals for us old timers and the newbies 5.56mm. It is just the ideal compromise. Target shooters are looking for the last tiny advantage so the 6mm has value to them.
                      This.

                      14 years ago, I would have been fine if they had first presented us with a .25 or .27 Grendel, but, heck, then again why not .26? .26 cal exactly splits the difference between .22 and .30. The intermediate of intermediate cartridges! Supreme efficiency balancing bullet mass, ballistics, and recoil.

                      I consider the 6.5 Grendel the best assault rifle cartridge possible within the confines of the AR platform, given high-capacity, double-stack magazines with a max 2.300 COL. This is why I love it.

                      It is also the best multi-role hunting cartridge in that platform.

                      It is also very good for informal target shooting, but technically and competitively speaking, is edged out in both drop and drift by a 6mm in the same case. (Or, as I've proposed above, a case stretched from 38.6mm to 40.4mm.)

                      So the 6.5 Grendel is a fantastic AR hunting round that can also be used for target shooting.

                      My proposed 6mmAR Turbo Stretched is a fantastic AR target round that can also be used for hunting.

                      Now, if we could get some of the newer hybrid, optimized ogives on long-range friendly 6.5mm 115-123 grain HPBTs, I think we could give 6mms a run for their money. Every time the major bullet makers come out with a "new" 6.5mm bullet with the same old fat, lazy tangent ogive (hello, Hornady 123gr ELD-M), I'm like, "Nooooo!!! Just put the Berger 140 Hybrid nose or Sierra 150 SMK nose on a 6.5mm 115gr and let us have a bit more velocity from the smaller Grendel case with a super sleek ogive. Why can't they just do it right the first time? It's so simple."
                      :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

                      :: I Drank the Water :: Revelation 21:6 ::

                      Comment

                      • CavityBackBullets
                        Bloodstained
                        • Nov 2016
                        • 98

                        #56
                        Originally posted by JASmith View Post
                        Claims like this stretch credibilty.

                        At some point one will need to disclose any “secret sauce” and demonstrate the perfomance claims are valid within acceltable pressure limits.
                        No disclosure when its someone elses case design and they shared the information with me.
                        What kills me with all this is why?
                        I mean Predatordown is as far as I know the Grendel long range king and he shoots mild loads out of his I believe 24in barrel at like 2450 fps.

                        Comment

                        • stanc
                          Banned
                          • Apr 2011
                          • 3430

                          #57
                          Challenge accepted!

                          Originally posted by BluntForceTrauma View Post
                          I don't trust 30 degrees. When the US Army developed what became 7.62 NATO, they began with a 30-degree shoulder, then soon reduced it to 20 degrees for reliable feeding.

                          No military rifle cartridges have a 30-degree shoulder. The steepest are 7.5x55 Swiss at 28 degrees, followed by 6.5x55 Swede at 25 degrees. All others are 23 degrees or less.

                          Originally posted by BluntForceTrauma View Post
                          Why not the 6.8 case cut down and necked down? Not as fat as a Grendel case, thus lacks capacity, thus lacks velocity.
                          High velocity is not necessary, according to the original (modest MV/high BC) design philosophy of 6.5 Grendel and the 6mm SAW (below).



                          Originally posted by BluntForceTrauma View Post
                          Thoughts from The Horde?
                          I would opt to use the Valkyrie case, necked up to 6mm, and shoulder angle reduced to 23 degrees. Fits in existing M68 links, for machine gun use.

                          Comment

                          • stanc
                            Banned
                            • Apr 2011
                            • 3430

                            #58
                            Originally posted by BluntForceTrauma View Post
                            I consider the 6.5 Grendel the best assault rifle cartridge possible within the confines of the AR platform, given high-capacity, double-stack magazines with a max 2.300 COL.
                            Taking into account military requirements, IMO the best assault rifle cartridge possible is the 5.45x39.

                            Comment

                            • BluntForceTrauma
                              Administrator
                              • Feb 2011
                              • 3897

                              #59
                              I consider the lack of 30 degrees to be simply hidebound, in-the-box thinking. But not the biggest deal. I strongly prefer 30, but could go either way. You gain a touch of case capacity and the supposed accuracy and throat-wear benefits, but nothing to write home about.

                              I could support a 6mm Valkyrie. And the 5.45x39 is a hell of a cartridge. One could do worse. . . . Both cartridges exhibit my approved "short case long bullet" principles.

                              A fully developed 6.5 Grendel (read developed and dedicated cartridges and loads) could have almost identical external ballistics and have a bit more mass for environmental barriers.
                              :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

                              :: I Drank the Water :: Revelation 21:6 ::

                              Comment

                              • stanc
                                Banned
                                • Apr 2011
                                • 3430

                                #60
                                Originally posted by BluntForceTrauma View Post
                                I consider the lack of 30 degrees to be simply hidebound, in-the-box thinking.
                                That could perhaps be true of some of the world's armies. Or perhaps military cartridge designers generally chose to err on the side of cautious conservatism in order to ensure reliable feeding.

                                In the case of 7.62 NATO developers, the evidence shows they were not hidebound in their thinking on this matter. When development started in 1945, instead of rigidly copying the 17-degree shoulder of the venerable .30-06 case, they elected to use a 30-degree shoulder. It was only after a few years of test and evaluation that shoulder angle was changed to 20 degrees, a fact which says to me that the 30-degree shoulder likely caused feeding or chambering issues.

                                Comment

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