Bolt Action Grendels and muzzle velocities

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  • Joseph5
    Warrior
    • Oct 2012
    • 370

    Bolt Action Grendels and muzzle velocities

    The new issue of Bandleader magazine has an article in it about the CZ 527 in 6.5 Grendel. What was interesting to me and was mentioned in the article is that even with a 24 inch barrel the muzzle velocities with factory and handholds were on average 100 fps below what is achieved in most AR 15's. Hornady Black was shown at 2453 fps and Custom SST was 2466. That is more in line with an 18 inch barreled AR and all of the handholds shown were around 100 fps or more below what would be expected. There have been a lot of reports about low muzzle velocities with HOWAs also. I just find it interesting?
  • DJL2
    Bloodstained
    • Aug 2017
    • 57

    #2
    Did they provide any speculation? Those velocities are indeed just a touch higher than what my 18 inch AR produces with that ammunition, but not enough to get excited about toting an additional 6 inches of barrel.

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    • LRRPF52
      Super Moderator
      • Sep 2014
      • 8569

      #3
      We have a thread on this: http://www.65grendel.com/forum/showt...-John-Haviland

      A lot of the loads weren't near max.

      People with Howa bolt guns have reported initial slower mvs, then they seem to speed up by 200fps with break-in. Might have something to do with hammer-forged barrels.
      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

      • SDguy
        Warrior
        • Oct 2015
        • 367

        #4
        Originally posted by LRRPF52 View Post
        We have a thread on this: http://www.65grendel.com/forum/showt...-John-Haviland

        A lot of the loads weren't near max.

        People with Howa bolt guns have reported initial slower mvs, then they seem to speed up by 200fps with break-in. Might have something to do with hammer-forged barrels.
        My initial thought was the bore diameter may be larger thus requiring a heavier powder charge to achieve similar pressure & velocity. The Part where they speed up with break in surprises me & blows my theory to pieces. How many rounds constitutes break in, on average roughly?

        Comment

        • gringo58
          Unwashed
          • Nov 2017
          • 2

          #5
          New CZ 527 American 24" barrel with 123 sst and 28.5 grs IMR 8208 XBR averages 2572 fps
          sd = 14 es = 38, shoots 3/4" at 100 yds.
          My 2 cents worth....

          Comment

          • ricsmall
            Warrior
            • Sep 2014
            • 987

            #6
            Most any rifle barrel speeds up after 100-200 rounds in my experience.
            Member since 2011, data lost in last hack attack

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            • LRRPF52
              Super Moderator
              • Sep 2014
              • 8569

              #7
              Originally posted by gringo58 View Post
              New CZ 527 American 24" barrel with 123 sst and 28.5 grs IMR 8208 XBR averages 2572 fps
              sd = 14 es = 38, shoots 3/4" at 100 yds.
              My 2 cents worth....
              Welcome aboard. That's good speed for 8208XBR under a 123gr SST from a 24" barrel.

              Plenty of performance too. With that kind of accuracy, I would just load that and drive on.

              You could push it more in the bolt gun, but who wants to mess with 3/4" at 100yds.
              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

              • gringo58
                Unwashed
                • Nov 2017
                • 2

                #8
                The 3/4' it is shooting is all needed for neck shots at Deer and head shots at Hogs. All I need, but I still have to remind myself that this Rifle is not a Bench rest rifle. Sure is a fun rifle, Love it. I will recheck speeds after a couple hundred rounds.

                Comment

                • SDguy
                  Warrior
                  • Oct 2015
                  • 367

                  #9
                  Originally posted by LRRPF52 View Post
                  Welcome aboard. That's good speed for 8208XBR under a 123gr SST from a 24" barrel.

                  Plenty of performance too. With that kind of accuracy, I would just load that and drive on.

                  You could push it more in the bolt gun, but who wants to mess with 3/4" at 100yds.
                  8208 is one of a number of propellants I would shy away from pushing the envelope with in Bolt action or otherwise. 8208 tends build pressure very fast as you approach and exceed book loads. My experience was I could not reach max book loads w 8208 without experiencing a sticky bolt in my CZ w an aftermarket CSS barrel for example.

                  Comment

                  • HowaGrendel
                    Bloodstained
                    • Sep 2017
                    • 99

                    #10
                    I have a Howa 20'' HBAR and with 100 grain Nosler B-tips speed runs up to 2700 with highest load I have tried with 8208......Berger 120 Target 2440.....Sierra 120 HPBT 2470 all with 8208.....at 2400 I got good groups with the Berger, at 2435 good groups with the Sierra....TAC so far has worked best in my rifle....still working with the 8208....I think I am going to quit using 120 or above weights, I want to try some 100 ELD's and a few other bullets in the 100 grain range...

                    Comment

                    • LRRPF52
                      Super Moderator
                      • Sep 2014
                      • 8569

                      #11
                      Originally posted by SDguy View Post
                      8208 is one of a number of propellants I would shy away from pushing the envelope with in Bolt action or otherwise. 8208 tends build pressure very fast as you approach and exceed book loads. My experience was I could not reach max book loads w 8208 without experiencing a sticky bolt in my CZ w an aftermarket CSS barrel for example.
                      Been saying that for years for use under 120-123gr bullets. If you look at Hodgdon's pressure test data on it, they couldn't get enough of it under a 100gr Nosler Ballistic Tip, but tapped out at 28.5gr under the 123gr SMK.

                      It's a great powder under 100gr-107gr cup and core bullets in 6.5 Grendel, and as long as you respect the pressure limit under 123gr, you're ok. They hit 50,000psi at 28.5gr, but it will spike after that under a 123gr for a lot of people.
                      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

                      • SDguy
                        Warrior
                        • Oct 2015
                        • 367

                        #12
                        Originally posted by HowaGrendel View Post
                        I have a Howa 20'' HBAR and with 100 grain Nosler B-tips speed runs up to 2700 with highest load I have tried with 8208......Berger 120 Target 2440.....Sierra 120 HPBT 2470 all with 8208.....at 2400 I got good groups with the Berger, at 2435 good groups with the Sierra....TAC so far has worked best in my rifle....still working with the 8208....I think I am going to quit using 120 or above weights, I want to try some 100 ELD's and a few other bullets in the 100 grain range...
                        I am an advocate for more data w Lever-evolution propellant with the 6.5 Grendel & 129 grain flat base cup & core bullets perhaps boat tail options as well. For compareson to the 100 grain offerings you mention I have reached those velocities & more with the heavier 125 & 129 grain projectile over Lever-evolution propellant, while experiencing respectable accuracy in my mini-action Grendel's w no pressure signs.

                        Hornady 129 Gr SP over LVR has been my preferred projectile when shooting for max energy harnessed for the 6.5 Grendel package. If you like the lighter weight bullets more power to you.

                        I happen to like the lighter 100 grain all copper bullets also. A 80 - 90 grain GMX would a super offering if we could talk Hornady into marketing these for the Grendel. As current offerings stand I favor the 100 gr Barnes for all copper offerings.
                        Last edited by SDguy; 11-30-2017, 01:19 AM.

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