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Thread: 224 Valkyrie...newest AR cartridge from Federal

  1. #71
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    This last week has uncovered a bad reamer probably several bad reamers floating around. Large contract barrel makers are making barrels for many companies using the incorrect reamers. The case length of factory brass as made is 1.585 +- the wall in the chamber where the case mouth should stop should be 1.610(SAAMI) plus the cone angle of .016 for a total gap of .041. The bad reamer has a dimensional error which makes the gap another .013" longer for a gap of .038" plus the cone of .016" for a total gap of .054". The bullets must span that gap from the case mouth to the start of the freebore. The freebore as measured in the bad chambers is .045 longer than the SAAMI chambers meaning the bullets have an extra .045" jump to the lands. That is likely hurting the accuracy with the factory loaded VLDs that need to be set close to the lands.

    The chamber will likely help those who plan to use lighter bullets in the 55-77gr range because they can seat them out further and gain powder capacity.
    You can figure out if you have a longer than SAAMI freebore by sticking a .224 inspection pin into the chamber and relating the length to the rim of the case or everyone can load the 90gr smk out to where they touch the lands and compare that measurement with others of different brands of barrels.
    SAAMI print below-
    IMG_1051.jpg
    Last edited by constructor; 06-10-18 at 09:39.
    AR15performance 68forums
    The 6.8 is the best choice for hunting deer and hogs with an AR15.

  2. #72
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    Quote Originally Posted by constructor View Post
    This last week has uncovered a bad reamer probably several bad reamers floating around. Large contract barrel makers are making barrels for many companies using the incorrect reamers. The case length of factory brass as made is 1.585 +- the wall in the chamber where the case mouth should stop should be 1.610(SAAMI) plus the cone angle of .016 for a total gap of .041. The bad reamer has a dimensional error which makes the gap another .013" longer for a gap of .038" plus the cone of .016" for a total gap of .054". The bullets must span that gap from the case mouth to the start of the freebore. The freebore as measured in the bad chambers is .045 longer than the SAAMI chambers meaning the bullets have an extra .045" jump to the lands. That is likely hurting the accuracy with the factory loaded VLDs that need to be set close to the lands.

    The chamber will likely help those who plan to use lighter bullets in the 55-77gr range because they can seat them out further and gain powder capacity.
    You can figure out if you have a longer than SAAMI freebore by sticking a .224 inspection pin into the chamber and relating the length to the rim of the case or everyone can load the 90gr smk out to where they touch the lands and compare that measurement with others of different brands of barrels.
    SAAMI print below-
    IMG_1051.jpg
    Great explanation. It makes sense since there seemed to be a yes/no distinction with the performance from maker to maker. Kind of a colossal cock-up on the newest and biggest new round roll out since 300BO. It seems to me that there still is an inherent issue with the 224V when it comes to trying to shoot 55-95 grain bullets in the same chamber?
    I just did two lines of powdered wig powder, cranked up some Lee Greenwood, and recited the BoR. - Outlander Systems

    I'm a professional WAGer - WillBrink /// "Comey is a smarmy, self righteous mix of J. Edgar Hoover and a gay Lurch from the "Adams Family"." -Averageman

  3. #73
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    I guess some people won't have to trim cases for a while.

  4. #74
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    Quote Originally Posted by FromMyColdDeadHand View Post
    Great explanation. It makes sense since there seemed to be a yes/no distinction with the performance from maker to maker. Kind of a colossal cock-up on the newest and biggest new round roll out since 300BO. It seems to me that there still is an inherent issue with the 224V when it comes to trying to shoot 55-95 grain bullets in the same chamber?
    copied from another forum-ETA 6/12/18- I chambered a short stub this morning to check the JGS reamer. This it where the bullets are .002" off the lands in a true SAAMI spec chamber. Measurements in barrels will be a little different due to headspace. They could be .005" longer.
    95gr SMK- 2.323"
    88ELD-2.323"
    90gr SMK-2.276"
    75ELD- 2.320
    77TMK-2.234-note the top of the boat tail is close to the shoulder junction where it should be, they do not protrude into the powder column much.
    80gr Berger-2.272

    The shorter bullets really work out ok since we need to keep apx .220" in the neck of the case to hold the bullet. The 77TMK set back to 2.23" which seems very short does not impact the powder capacity because the case is short. The boat tail is in the shoulder area right where it should be. The 55gr Nosler have to be set back around 2.117-2.180 to keep them out of the lands but again they do not go too far into the powder column. It all works out much better than we would first think.
    AR15performance 68forums
    The 6.8 is the best choice for hunting deer and hogs with an AR15.

  5. #75
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    But aren't those longer than standard mag length for the heavier bullets? The 90 and 77gr would be OK, but the others a bit too long?
    I just did two lines of powdered wig powder, cranked up some Lee Greenwood, and recited the BoR. - Outlander Systems

    I'm a professional WAGer - WillBrink /// "Comey is a smarmy, self righteous mix of J. Edgar Hoover and a gay Lurch from the "Adams Family"." -Averageman

  6. #76
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    Quote Originally Posted by FromMyColdDeadHand View Post
    But aren't those longer than standard mag length for the heavier bullets? The 90 and 77gr would be OK, but the others a bit too long?
    Yes, unless they use a windowed mag from Cavity Back bullets or single feed. Most 6.8 mags allow loading to 2.295 or 2.3".
    The ELDs may shoot pretty good with .020 jump. Just never know until we can test in a SAAMI spec chamber. As it is most are loading to 2.28 and have a .050-.070 jump to the lands because of the out of spec reamers.
    AR15performance 68forums
    The 6.8 is the best choice for hunting deer and hogs with an AR15.

  7. #77
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    I'm an engineering idiot, but it seems like the 224V by the numbers is a compromise. And I guess that is the key, by the numbers. It has the such wide range of applicability for projectiles and uses, while using as many common parts as possible- it was bound to not be optimal in all respects.

    To me, it would seem that they didn't go wide enough in the cartridge. It seems that a 30RAR neck down would have better fit the bill of launching heavies at speed. But then you are talking wholly different uppers, single stack mags which would drive up the costs and the 'AR15' ness of the gun. The ammo would cost more. (Just looking over things, it seems a 30R-AR necked down to 6mm would be a sweet little hot round from an AR.)

    Those Hornady 95gr bullets look like a sweet round- but are they going to be able to get them to work?

    I guess we'll just have to see how the rifles shoot when they are set up right, but I'd say that now I've gone from getting back in line for a JP upper to waiting for next year to see how everything shakes out.
    I just did two lines of powdered wig powder, cranked up some Lee Greenwood, and recited the BoR. - Outlander Systems

    I'm a professional WAGer - WillBrink /// "Comey is a smarmy, self righteous mix of J. Edgar Hoover and a gay Lurch from the "Adams Family"." -Averageman

  8. #78
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    The 95SMKs shoot better than the 90s out of my barrels when I seat them out close to the lands. I think Hornady's 88s will be more forgiving of the jump. I have a box just haven't had time to shoot them yet.
    AR15performance 68forums
    The 6.8 is the best choice for hunting deer and hogs with an AR15.

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