View Poll Results: Which would you choose?

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  • 6.5mm Grendel

    5 33.33%
  • 6.8mm SPC

    10 66.67%
Multiple Choice Poll.
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Thread: This -><- close to choosing 6.8 SPC vs 6.5 grendel

  1. #61
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    Quote Originally Posted by constructor View Post
    Yes there was. The SAAMI print had a .050" long freebore. The 115gr bullets Hornady made at the time were jammed into the landsÖ Chris Murray has said before the print turned in to SAAMI was an early designÖ
    Yes, the more ďmatchĒ chamber design got sent to Remington, who sent it to SAAMI. SAAMI simply published the new standard as it was submitted, they didnít mess anything up, or guarantee it would match development hand load velocity. Some early bullets were not well designed for the submitted chamber, they needed to be redesigned. These were both minor issues and not some giant problem that should have doomed the 6.8, but for the proponents overreaction. I never saw 50-100fps being worth turning off a huge chunk of people who wonít own one now. I still think itís the most practical amount of power you can fit in an AR15.

    Bringing in an industry partner for more of the development, not just to submit to SAAMI, and more development with ammo manufacturers are lessons mostly learned.

    Quote Originally Posted by constructor View Post
    A mistake on a reamer print from PTG around 2006 caused the second problem.
    Thatís a manufacturing problem, not the SAAMI spec. Iím actually the guy who noticed the shaved copper rings.

  2. #62
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    Quote Originally Posted by Todd.K View Post
    Yes, the more “match” chamber design got sent to Remington, who sent it to SAAMI. SAAMI simply published the new standard as it was submitted, they didn’t mess anything up, or guarantee it would match development hand load velocity. Some early bullets were not well designed for the submitted chamber, they needed to be redesigned. These were both minor issues and not some giant problem that should have doomed the 6.8, but for the proponents overreaction. I never saw 50-100fps being worth turning off a huge chunk of people who won’t own one now. I still think it’s the most practical amount of power you can fit in an AR15.

    Bringing in an industry partner for more of the development, not just to submit to SAAMI, and more development with ammo manufacturers are lessons mostly learned.



    That’s a manufacturing problem, not the SAAMI spec. I’m actually the guy who noticed the shaved copper rings.
    I know it wasn't SAAMI spec. someone at PTG transposed a number, it should have been 1.7109" not 1.7019".
    "A guy that noticed the copper rings". In Jan 2006 I unloaded a cartridge and stuck on the bullet was a ring. I called Art and asked him about it, he just said it happens but wasn't sure why at the time. Later that year I found the transposed number on the PTG print and tried with 6 emails to get Dave to understand the mistake. I finally gave up and designed a new reamer with a 35 degree angle at the end of the case mouth and .085" freebore and told PTG to just make the reamer as I had drawn it. I went back and forth with them for a few years because sometimes they would just send me a standard 6.8x43 reamer instead of using my drawing. I ended up going to JGS for all of my reamers.
    At any rate the reamer everyone calls the SPCII is the one that has a .100" freebore and we have proven several times over we can load heavier charges and get a lot more velocity in barrels using that chamber.
    At a time when every other statement was "the Grendel shoots flatter" the extra velocity was important for comparison to show the level of performance the 6.8 could have when made correctly. Guys that want to go to the store and buy ammo off the shelf can still do that. Guys that want to shoot 130 gr Bergers at 2600fps can do that too.
    Last edited by constructor; 09-21-21 at 17:38. Reason: y
    AR15 Performance
    The 6.8 is the best choice for hunting deer and hogs with an AR15.

  3. #63
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    I used to work at Noveske. So when I found the rings Johnny, Art, and Dave got the problem figured out.

    I agree the longer freebore is more appropriate/better for an AR. But Itís not reasonable to believe your velocity numbers could be attained in a pressure test barrel. The majority of the velocity loss was proper testing for commercial loading and not the match chamber.

    All this focus on a little velocity is still turning off a lot of potential users from a really useful cartridge.

  4. #64
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    Quote Originally Posted by Todd.K View Post
    I used to work at Noveske. So when I found the rings Johnny, Art, and Dave got the problem figured out.

    I agree the longer freebore is more appropriate/better for an AR. But Itís not reasonable to believe your velocity numbers could be attained in a pressure test barrel. The majority of the velocity loss was proper testing for commercial loading and not the match chamber.

    All this focus on a little velocity is still turning off a lot of potential users from a really useful cartridge.
    So you guys were using the SPCII reamer design from PTG and that is what John called the mod 1?
    We ran the tests with a Pressure Trace system and I made a piezo test barrel for Art in early 2008. I think all of the SAAMI and SPCII wars were fought back in 2007 and 8 and everyone understands the value of the SPCII or other improved chambers and rifling.
    I was getting blanks from PAC NOR back then until fall of 2008 and tested 11, 12 and 13 twist barrels, they made the 12 twist button for me after we completed the 6.8 performance test down at Wild River Ranch in Texas. Seems like you guys changed twist rates shortly after, you guys used to make your barrels at PAC NORs facility didn't you?
    We tested several barrels but the difference between a 13 twist 3 groove with my DMR chamber and a DPMS with 10 twist SAAMI chamber was 13,000psi (DPMS 13k higher)using the same SSA ammo, from the same box.
    As for tuning some people off, yeah I guess it could have but I still can't make 6.8 barrels fast enough to meet the demand and that isn't why the military didn't adopt it. Even Mattis said they couldn't justify the expense, loved the idea but couldn't approve it.
    AR15 Performance
    The 6.8 is the best choice for hunting deer and hogs with an AR15.

  5. #65
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    The move to 12 twist came with Johnís take on the SPCII chamber. I never got too deep into all the chamber details but I know it had similar freebore.

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