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What do you think of the 6.8mm, looks like the Army will switch to it

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  • ojrojr Senior Member Posts: 1,143 Senior Member
    Somebody with more knowledge than me will correct me I'm sure and thats ok
    Didn't the Brits experiment with a 280 cartridge as a submission for a standard Nato cartridge just after ww11 and was't this rejected  [by the mainly huge American influence] in favour of the short 30 cal, ie 308 or 7.62?

    I'm with tennmike here, the whole of us , the whole western world, nato etc should adopt a short action 6.5 caliber.


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  • SpkSpk Senior Member Posts: 4,298 Senior Member
    We can debate 6.5 or 6.8 but I'm more interested in the cartridge itself. If they're using something beside a 30 Remington case then what will be the spec's on the new cartridge. 

    Wasn't there some big noise about running the chamber pressures up to "tank" power levels just a little while back. A new gun might make sense if they go in this direction. And if they do go this route, there will probably be plenty of bullets to choose from once they commercialize the whole smash.

    Guess we'll see what happens.
    Never argue with stupid people, they will drag you down to their level and then beat you with experience -- Mark Twain
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  • das68das68 Posts: 662 Senior Member
    edited December 2018 #34
    ojr said:
    Somebody with more knowledge than me will correct me I'm sure and thats ok
    Didn't the Brits experiment with a 280 cartridge as a submission for a standard Nato cartridge just after ww11 and was't this rejected  [by the mainly huge American influence] in favour of the short 30 cal, ie 308 or 7.62?



    this


    in the  EM-2






    at least one Brit still experimenting


     7mm Mk1Z        resized  .243         resized .308        .308 case.





    he is now using reformed .300 Savage I think.



    it works

    Roe doe Barnes TSX 140 grain at 200 yards.














  • Big ChiefBig Chief Senior Member Posts: 32,995 Senior Member
    edited December 2018 #35
    Spk said:

    Wasn't there some big noise about running the chamber pressures up to "tank" power levels just a little while back.
    I've seen a couple articles about the new cartridge having pressure like a Tank.......I don't know where or when this metric was started as a measurement and selling point of the 6.8mm and making it more lethal. I had to do a double take.

    I thought ME ( and down range ballistics)/BC/Velocity and others were the gold standard.

    I wondered are they saying because it has high chamber pressure like a tanks main gun it will make it superior cartridge. They are using this a selling point. Strange way to describe what the cartridge ballistics are. 

    Maybe it impresses those who control purse strings?


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  • Uncle FesterUncle Fester Senior Member Posts: 1,440 Senior Member
    Big Chief said:
    Spk said:

    Wasn't there some big noise about running the chamber pressures up to "tank" power levels just a little while back.
    I've seen a couple articles about the new cartridge having pressure like a Tank.......I don't know where or when this metric was started as a measurement and selling point of the 6.8mm and making it more lethal. I had to do a double take.

    I thought ME ( and down range ballistics)/BC/Velocity and others were the gold standard.

    I wondered are they saying because it has high chamber pressure like a tanks main gun it will make it superior cartridge. They are using this a selling point. Strange way to describe what the cartridge ballistics are. 

    Maybe it impresses those who control purse strings?


    According to this source, the main gun on a M1 tank has a peak chamber pressure of around 74,000psi.  
    http://www.inetres.com/gp/military/cv/weapon/M256.html

    Since the mild recoiling 6.5mm creedmore comes in at around 62,000psi, designing  the new round to reach “Tank Pressures” wouldn’t be that hard.  Weather that is a good idea/goal, I doubt it.  Most modern rifles seem to top out in the 65,000 psi range.  


    While I understand the cost issues outlined by others above, I think recent wars have led the military to have another “Krag” epiphany.  Just as the Krag round wasn’t good enough, they think 5.56mm round just isn’t good enough anymore. It doesn’t have the range they want and it wasn’t designed with modern body armor in mind.

    Personally, I don’t think the performance difference between a 6.5mm and a 6.8mm round is likely to be material. Either way, they should be able to get the range they want and an upgrade in stopping power. 

  • Big ChiefBig Chief Senior Member Posts: 32,995 Senior Member
    I think the service round will have a polymer case.

    Remember bullet weight will be standardized just as the 5.56 is 62 grain for the military so comparing the 6.8 to lighter/heavier bullets is only for civilians/reloaders. They are designing this cartridge for military use and there is no consideration for civilian use.

    If it allows our Warfighters to whack the Islamofacist and any enemy better than the 5.56, I'm all for it.


    It's only true if it's on this forum where opinions are facts and facts are opinions
    Words of wisdom from Big Chief: Flush twice, it's a long way to the Mess Hall
    I'd rather have my sister work in a whorehouse than own another Taurus!
  • BigDanSBigDanS Senior Member Posts: 6,992 Senior Member
    Open sight distances vs. optics.  Yes a good shot can hit a 200 yards or 300 yard man sized target with open sights, but they are looking pretty small.  Within the 200 yard range, I am sure this will provide additional energy, moving from 1000 fpe to around 2000 fpe.  That's a big difference.  The average soldier needs to see the target as well.
    "A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
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  • tennmiketennmike Senior Member Posts: 27,457 Senior Member
    Running the peak chamber pressure up to 74,000psi can be done, but they will have two new problems to deal with doing that.

    At that pressure and resulting velocity, there will be some copper fouling to be dealt with. That's been known since the .22-250 made its debut, and same for the .17 Rem. Copper fouling isn't all that hard to deal with in your home/man cave, but think about the problems in the field.

    They will have to make a highly temperature stable powder for the firearms. Anyone that has reloaded on the high side of the reloading data, or exceeded it, and shot ammo that has been in high temps (95° +) and in direct sunlight has probably experienced a sticky bolt. A powder that is not affected by temperature changes will be a must.

    Another thing to consider is the barrel of the rifle. It will have to be thicker from breech to about mid barrel to handle the increased pressure. Rifle weight will increase as well as felt recoil. That was the main gripe with the M1 and M14 rifles.
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