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Thread: 69 grain TMK vs 77 grain TMK for defense use from a SBR

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    69 grain TMK vs 77 grain TMK for defense use from a SBR

    I am wondering if 69 grain TMK would have better terminal ballistics in barrels under 10 inches over the 77 grain TMK because of the higher velocity?

    My thinking is that if the 69 and 77 grain TMK's have the same construction and are both comparably on the "heavy" side... a similar impact velocity with the 69 grain and 77 grain would yield similar fragmentation and penetration results
    Last edited by brycewise; 12-05-17 at 19:24.

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    Quote Originally Posted by brycewise View Post
    I am wondering if 69 grain TMK would have better terminal ballistics in barrels under 10 inches over the 77 grain TMK because of the higher velocity?

    My thinking is that if the 69 and 77 grain TMK's have the same construction and are both comparably on the "heavy" side... a similar impact velocity with the 69 grain and 77 grain would yield similar fragmentation and penetration results
    What do you plan on shooting? What do you consider better terminal ballistics? Greater Penetration? Greater Fragmentation?

    From Black Hills:
    83D0E37E-82C2-4E61-960A-073494B5C9B4.jpg

    B1ABAC64-1D4C-473D-AA6D-E529116C639F.jpg
    AQ planned for years and sent their A team to carry out the attacks, and on Flight 93 they were thwarted by a pick-up team made up of United Frequent Fliers. Many people look at 9/11 and wonder how we can stop an enemy like that. I look at FL93 and wonder, "How can we lose?". -- FromMyColdDeadHand

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    From those above gel shots, neither is ideal as shown, per FBI standards.

    The 77 has adequate penetration, but a long neck length.

    The 69 has a short neck, but insufficient penetration.

    As for these from a shorter barrel, higher velocity tends to make for more violent upset, while lower velocity tends to produce later upset and deeper penetration.

    Based on that without any testing, the 69 should be the better choice from the 10.5" as it should retain the short neck while increasing penetration somewhat.

    It could actually show better gel performance from the 10.5" than the 16"

    But, many things in terminal ballistics are hard to predict, so the only real way to tell is to do the testing and see the results.
    Last edited by Clint; 12-05-17 at 22:04.
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    Quote Originally Posted by ggammell View Post
    What do you plan on shooting? What do you consider better terminal ballistics? Greater Penetration? Greater Fragmentation?

    From Black Hills:
    83D0E37E-82C2-4E61-960A-073494B5C9B4.jpg

    B1ABAC64-1D4C-473D-AA6D-E529116C639F.jpg
    They would be used as defense rounds where barrier penetration is not a factor. I would like to have 12 inches of penetration with fragmentation. The black hills testing photos are with 14.5 and 16 inch barrels. I would be getting about 300 to 400 fps less then what those barrel lengths produce, which will probably hurt in the fragmentation dept but help in the penetration dept.

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    Those gel pics are apples and oranges, due to one being SMK, and the other TMK.

    77 TMK, 11.5”Bbl gelatin:
    https://m.youtube.com/watch?v=qXBU03vdr2Q
    Good performance.
    Last edited by 1168; 12-06-17 at 03:42. Reason: Add

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    Quote Originally Posted by 1168 View Post
    Those gel pics are apples and oranges, due to one being SMK, and the other TMK.
    You’re right. Thought I got the SMK for both.
    AQ planned for years and sent their A team to carry out the attacks, and on Flight 93 they were thwarted by a pick-up team made up of United Frequent Fliers. Many people look at 9/11 and wonder how we can stop an enemy like that. I look at FL93 and wonder, "How can we lose?". -- FromMyColdDeadHand

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    Quote Originally Posted by ggammell View Post
    You’re right. Thought I got the SMK for both.
    Thanks for providing them, though. I always enjoy seeing dead jello.

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