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Thread: 7.62 / 6.5 / 5.56 vs concrete block

  1. #1
    Chieftain stanc's Avatar
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    7.62 / 6.5 / 5.56 vs concrete block

    Was intending to put this video in the .308 vs 6.5 Grendel thread, but it appears that got deleted. So, since this section didn't seem busy, I'm putting it here although it ain't your typical target.

    (Mods feel free to move it elsewhere, if you wish.)


  2. #2
    Moderator bwaites's Avatar
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    ”You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt

  3. #3
    QuadCam
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    i was thinking the m855 with the steel penetrator core would have penetrated through all the jugs. I guess not.

  4. #4
    Moderator bwaites's Avatar
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    Quote Originally Posted by QuadCam View Post
    i was thinking the m855 with the steel penetrator core would have penetrated through all the jugs. I guess not.
    855 is a bit of a compromise as an AP. Once it hits something, the jacket seems to come apart. The penetrator sometimes keeps going, as it did in this case, when it exited the side of the jug.

    I would like to see this test with the Barnes solid 110 grain.

    Going to have to give it a try.
    ”You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt

  5. #5
    JASmith
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    It appears that the steel core still makes a big difference since it got through at least as well as the others and was the lightest of the bunch.

    The mantra is "bullet construction counts!"

  6. #6
    Chieftain stanc's Avatar
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    Quote Originally Posted by QuadCam View Post
    i was thinking the m855 with the steel penetrator core would have penetrated through all the jugs. I guess not.
    As Bill noted, bullet construction of M855 is relatively fragile, with a much thinner jacket than larger calibers.

    Also, for tough barriers like this, there's no substitute for mass. Even though the 7.62 and 6.5 MatchKings lack the steel tip of M855, their post-barrier effects were far greater.

  7. #7
    JASmith
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    The core separating from the rest of the bullet should be no surprise.

    They need to do that so the harder material can do its thing.

    It's too early to generalize about the value of mass. While mass and the KE associated with it makes exciting splashes, one needs the bullet to get through in order to get on the table for effects. The lighter M855 core penetrated as far as anything else and was a lot lighter. Hence one could also draw the conclusion that there's no substitute for steel, since the M855 was the only round with a steel core.
    Last edited by JASmith; 08-20-2011 at 05:29 PM.

  8. #8
    Chieftain stanc's Avatar
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    Quote Originally Posted by JASmith View Post
    The core separating from the rest of the bullet should be no surprise.

    They need to do that so the harder material can do its thing.
    Huh?
    It's too early to generalize about the value of mass.
    Too early for you, perhaps, but not for me. In similar barrier penetration testing I did in the past, I observed that heavier bullets always outperformed lighter bullets, despite a velocity differential of 300 fps.

    Rifle calibers (7.62mm 147gr FMJ vs 5.56mm 55gr FMJ) and pistol calibers (.45 ACP 230gr FMJ vs 9mm 115gr FMJ), the result was the same.
    While mass and the KE associated with it makes exciting splashes, one needs the bullet to get through in order to get on the table for effects.
    Uh, don't you realize that the "exciting splashes" were caused by the bullets getting through???
    The lighter M855 core penetrated as far as anything else and was a lot lighter.
    True, but its post-barrier effect was far less than those of the bigger, heavier bullets.
    Hence one could also draw the conclusion that there's no substitute for steel, since the M855 was the only round with a steel core.
    Incorrect conclusion. Note the difference in post-barrier wound trauma of 5.56 M855 vs 6.8 M855-type bullet.



    There is no substitute for mass.

  9. #9
    JASmith
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    I think the difference in how one interprets the information is the focus on a single dimension or effect versus looking at the challenge as a constrained system where trades need to be made.

    As near as I can tell, the context of almost any discussion in this forum is the Grendel. My interest is in what bullet designs, etc. might help it perform better in various encounters.

    To be sure, mass is important, but it is only a part of the system and the Grendel platform puts significant constraints on the mass that can be brought to the problem.

    I will repeat, one has to get through any intervening material before the response in gel (or any liquid) begins to be important.

    Further, the milk jug tests more closely illustrate the dynamic wound cavity than the permanent wound cavity. Martin Fackler and others have shown that the dynamic cavity, while capable of presenting spectacular pictures, does not adequately represent wound potential in torso-sized objects with individual weapons.

    To illustrate, consider the difference in how that milk jug responds to the 5.56 to how a 5 gallon plastic can will. Or to get more graphic, a squirrel coming apart when hit by that round versus a small hole in a deer - both responses from the same bullet at the same velocity. You just can't count on the dynamic cavity causing significant damage unless the body is small enough that the skin (or package) ruptures.

    To repeat:
    1) Hydrodynamic shock, while interesting, is a minor player in the terminal effects the Grendel needs to generate.

    2) When working to get the most out of a cartridge, trades in penetration, energy, and bullet construction are needed.

    Bottom Line: If the purpose of this thread is merely to entertain, then I will read with amusement. If, however, the comments appear to impact the Grendel (or other cartridge) design space, I will likely add more comments.

  10. #10
    Chieftain stanc's Avatar
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    Quote Originally Posted by JASmith View Post
    To be sure, mass is important, but it is only a part of the system and the Grendel platform puts significant constraints on the mass that can be brought to the problem.

    I will repeat, one has to get through any intervening material before the response in gel (or any liquid) begins to be important.
    Does this mean you still don't understand that the 6.5 and 7.62 MatchKings did get through the barrier???
    Bottom Line: If the purpose of this thread is merely to entertain, then I will read with amusement. If, however, the comments appear to impact the Grendel (or other cartridge) design space, I will likely add more comments.
    Comment all you wish. But it'd be nice if you show evidence that supports your claims, instead of just posting your beliefs.

  11. #11
    JASmith
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    Quote Originally Posted by stanc View Post
    Does this mean you still don't understand that the 6.5 and 7.62 MatchKings did get through the barrier???

    Comment all you wish. But it'd be nice if you show evidence that supports your claims, instead of just posting your beliefs.
    My apologies, I keep forgetting that 30+ years in the weapons business makes me forgetful that some basic truths aren't obvious.

  12. #12
    kamrr4437
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    Very informative video. Never seen anything done on the 6.5 grendel like this. I must say even though it was smaller than the .308 i would say it held up nicely in doing the job. I would have liked to have seen an amax or a scenar but still was very good. You can see the extra womp the .308 put on it. But this video does prove that the 6.5 will do the job on any human especially since they dont wear bricks most of the time lol . Not to mention the grendel would do better at extended ranges. I also have to say i was proud of the little 5.56 i was aware that block like that was a weak point for the 5.56 but given the terms of the test and size of that bullet it still did a good job. In a zombie killing situation i wouldnt be firing one round anyway so getting several on target quickly and having them work effectively is good. Great test i enjoyed the video. I believe this is the same man that did the test with m855 with the metal and the beef rib, roast and jello to see the results and that was a good video for the 5.56 as well. Thanks for sharing this video. Good stuff!

    Keith

  13. #13
    LRRPF52
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    We need to do this test at 500m now between the Grendel and 7.62 NATO M80, M118, and M852. Who knows what the Grendel will do...

  14. #14
    Chieftain stanc's Avatar
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    500 meters!!! Who knows what any of them will do at that range. Might be interesting to see, though. Too bad there's no 6.5 FMJ to put up against 7.62 M80.

  15. #15
    JASmith
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    Quote Originally Posted by stanc View Post
    ...Too bad there's no 6.5 FMJ to put up against 7.62 M80.
    True, it would be nice to have FMJ across the board. On the other hand, using SMK bullets for each of the calibers tested will give a good relative comparison.

    I'm really hoping someone can scare up some 6.5 AP bullets for the test.

  16. #16
    Moderator bwaites's Avatar
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    Quote Originally Posted by stanc View Post
    500 meters!!! Who knows what any of them will do at that range. Might be interesting to see, though. Too bad there's no 6.5 FMJ to put up against 7.62 M80.
    Well, if I can prevail upon my source for 20-30 more bullets, I can use the 120 grain FMJ Norma.

    Then it becomes simply finding the right day without wind.
    ”You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt

  17. #17
    RStewart
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    My conclusion- I would not want to be just on the other side of 2-3 inches of cinder block and be shot at by any of them. But, I am a simple guy.

  18. #18
    kamrr4437
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    My conclusion- I would not want to be just on the other side of 2-3 inches of cinder block and be shot at by any of them. But, I am a simple guy.
    ^
    Exactly my thoughts as well RStewart.

  19. #19
    warped
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    Quote Originally Posted by RStewart View Post
    My conclusion- I would not want to be just on the other side of 2-3 inches of cinder block and be shot at by any of them. But, I am a simple guy.
    We learned long ago that it was always better to give than to receive!

    I think you remember that it applies to many things...

  20. #20
    LRRPF52
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    Our sister Battalion in OIF had come under heavy fire in an urban area during the initial push up to Baghdad. I talked with one of the guys from that unit later in 2004, and he said he was just doing what he had been trained to do when he was in Ranger Regiment before coming to the 82nd...i.e. bounding with fires toward the enemy. They started taking fire from a Dshk heavy machinegun, and were pinned down on a city street. He called up his buddy on his ICOM. Previously, the dude had been complaining about being assigned the Barrett M107 .50 BMG. He was providing support for this particular line unit, and responded via his ICOM radio that he was already on it. A pause, a few coughs from the Barrett...and Dshk no longer an issue.

    The Dshk gunners had been emplaced in a well-fortified gun position with plenty of cover to defeat small arms fire, including a block wall. This guy said that when they advanced onto the gun position, it looked like someone had just finished a water-melon smashing contest. The .50 had totally devastated the Iraqis behind the wall. From then on, the guy with the Barrett could often be seen cradling it...talking to it at times, never letting it out of his immediate control. That's 29 pounds of bad news if you're on the receiving end of that deal...

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