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  • stanc
    Banned
    • Apr 2011
    • 3430

    #16
    Originally posted by rwh View Post
    What's the cartridge in the middle? Looks like a 6x45 ackley?
    6x45 Brunswick

    Tom You have a couple of the many variations of the SAW cartridge. The steel FA 73 round is the final iteration that was tested extensively. It is the XM732 Ball. The aluminum round is a lengthened one developed as an alternate to a steel or brass case. I’m not aware of an XM designation for it. The center cartridge in the photo below is one submitted for test by the Brunswick Corp. None of the 6mm SAW cartridges were adopted. If you do a search you’ll find descriptions and photos of man...

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    • stanc
      Banned
      • Apr 2011
      • 3430

      #17
      Originally posted by bj139 View Post
      I just bought the last one of these. I couldn't resist the price.
      I posted back in the spring how I would end up at 6x45.


      This article influenced my decision. Now I need dies.
      http://www.chuckhawks.com/6mm_military_cartridge.htm
      6mm-.223 would not be my choice for a 6mm "main battle cartridge able to carry the goods to 600-800 meters in a suppressive fire mode from a machine gun, and to 500-600 meters from a rifle."

      If limited to 5.56x45 COL, I'd opt for the 6x41 (6.8 SPC parent case, shortened and necked down). Uses longer, more streamlined, higher BC projectiles than the 6x45, driven to faster velocities.

      Last edited by stanc; 12-17-2017, 06:13 PM.

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      • bj139
        Chieftain
        • Mar 2017
        • 1968

        #18
        The 6mm-223 would provide a noticeable increase in momentum (mass x velocity) while not having a very big weight penalty and would only be a barrel and ammunition change.

        In the article I posted, I don't think he says these would be useful for machine guns.

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        • stanc
          Banned
          • Apr 2011
          • 3430

          #19
          Originally posted by bj139 View Post
          In the article I posted, I don't think he says these would be useful for machine guns.
          From the article: "...main battle cartridge able to carry the goods to 600-800 meters in a suppressive fire mode from a machine gun..."

          He also wrote: "[6mm-223] should be able to drive an 85 grain bullet to 3000 fps. Its overall length, head size, case capacity, shoulder angle, etc. are identical to the current 5.56 NATO cartridge, so it could easily be adapted to current 5.56mm weapons merely by re-barreling."

          The current 5.56mm weapons used by the US Army have a 14.5" barrel length. I doubt that 6mm-223 could push an 85gr bullet to anywhere near 3000 fps from a 14.5" barrel. Maybe 2600 fps, if that.

          He followed with: "A FMJ 6mm bullet of boat tail spitzer form weighing 85 grains has an adequately high ballistic coefficient to make an excellent long range bullet..."

          I don't know of any company that offers an 85gr FMJ, but Sierra has a 90gr FMJ that was developed specifically for the 6mm-223, and its BC is a mediocre 0.376 in the range of 2100-2800 fps.

          Complicating matters further is that the article was written in 2002, long before lead-free bullets became mandated. Lead-free projectiles for 6mm-223 will either weigh less than 85gr -- and therefore have even lower BC, reducing long range capability -- or will have a much longer base, which will reduce powder capacity and muzzle velocity. This would be even worse for Tracer bullets, which are typically longer than Ball projectiles.

          There was a time when I thought 6mm-223 would be a good alternative to 5.56x45 (http://www.benning.army.mil/magazine..._4/06_pf01.pdf). But, it is just not the best option for an 800-meter cartridge.

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          • bj139
            Chieftain
            • Mar 2017
            • 1968

            #20
            My bad. I didn't catch that since "from a machine gun" was on the next line.

            Hodgdenreloading.com shows an 85g bullet at 2800fps at 49,000psi from a 24" barrel.

            If loaded to the same pressure as 5.56 it might make 3000fps.

            Lead free projectiles are mandated? How about radioactive uranium free projectiles? I thought that was only in California.

            I agree that nothing is as good as the 30-06, except when you have to carry all the ammo and the rifle.

            There is no one best choice, just a series of compromises.

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            • LRRPF52
              Super Moderator
              • Sep 2014
              • 8569

              #21
              Originally posted by bj139 View Post
              I just bought the last one of these. I couldn't resist the price.
              I posted back in the spring how I would end up at 6x45.


              This article influenced my decision. Now I need dies.


              Would there be a potential safety problem or will 6x45 not chamber in a 5.56 chamber?
              I'm thinking it won't.
              The 6x45 SAW we're talking about is a totally different cartridge than the 6x45 (6mm .223 variant).

              6x45 SAW has a fatter case with 2.580" COL, optimized around a 105gr bullet with a high BC. The only things in common with 6x45 SAW and 6x45 are the numbers. Performance differences are quite considerable, as are the actions required to cycle each.
              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

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              • Essayons
                Unwashed
                • Oct 2015
                • 22

                #22
                I don't know if the USSR started from a blank slate when they developed this one, but here's another 6x49 solution: http://modernfirearms.net/en/machine...annyj-6mm-eng/ Can anyone here point me to more info on the USSR's 6x49 Unified Machinegun project?

                1311310072.jpg

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                • stanc
                  Banned
                  • Apr 2011
                  • 3430

                  #23
                  I've not seen much info on the 6x49 beyond that on the page you linked.

                  TFB article: http://www.thefirearmblog.com/blog/2...x49mm-unified/

                  IIRC Russki color codes, below are (from l. to r.) Ball, AP, API projectiles.



                  FYI, a 6x53 preceded the 6x49. Looked similar to the .243 Win (below).
                  Except the 6x53 case was a tiny bit fatter, and had a little more taper.

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                  • stanc
                    Banned
                    • Apr 2011
                    • 3430

                    #24
                    Grendel's Grandfather?

                    Speaking of Russian experimental cartridges, I came across pics of an interesting 7.62mm round developed circa 1962.
                    The 7.62x40 (also called 7.62x41) looks like 6.5 Grendel on steroids, and was reportedly intended to replace 7.62x54R.
                    Anyone who can read Russian may wish to check out the two magazine articles posted at: http://popgun.ru/viewtopic.php?f=281&t=257424&start=90

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