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Thread: Temporary Cavitation Wounding. Rifle vs. Pistol?

  1. #11
    Member Balisong's Avatar
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    Quote Originally Posted by DocGKR View Post
    Definitely post-mortem from Medical Examiners office...

    This is one of the seminal incidents that encouraged American SWAT teams to switch from MP5's to AR15's.
    That's interesting. As always, I appreciate you sharing your knowledge and expertise with us. I didn't realize there were specific instances that lead to the change. That being said, I do wonder how differently that shooting would have gone if the team had heavier rounds from your list in their MP5s....

  2. #12
    Thanks for the excellent information Doc and every! I have some followup questions based on what I've learned thus far.

    1.) From the example (1500fps slugs vs. 6000fps tiny bullets) I understand that at a given surface area (and KE?) there is going to be a velocity threshold at which temporary caviation wounding beings and it accelerates from there. Depending on the bullet (expansion, weight, etc) this might be low (like the slug), high (like I'm assuming 62gr 5.56 is), or impossible to achieve. So to sort of re-phrase my question from the OP (ignoring bullet construction issue for the moment) approximately what velocity is needed to have .355 or .4005 bullets which are expanding into the .5-.7in range start to show significant TCW similar to that of intermediate caliber rifles? Say for example, a 5.56 SBR pushing 77gr OTMs to 2500fps or similar?

    2.) Onto bullet construction, I understand that pistol bullets (like rifle bullets) have a certain velocity window in which they will terminally perform properly. If pushed beyond this window, they will act like a varmit bullet and have very poor penetration. For these particular pistol bullets specifically, it does seem that limits you to the solid-copper and similar HP designs like the Barnes TACXP. As you point out Doc, these have a tenancy to have the petals fold back against the body at higher velocities. The two tests I could find certainly showed as much: #1, #2. That does still seem to leave the bullet somewhat expanded however, seemingly in the .5in-.6in range. At least at 1550fps the 80gr TACXP still seems to be meeting the FBI spec as well. Not apples to apples, but so does the 125gr TACXP when shot at ~1500fps in 10mm. If this performance (level of expansion and penetration) continue up to the 1900-2100fps range (as both barnes and DT assure me it will, and if it doesn't the 95gr or even 115gr TACXP could be used instead), it seems they would be an effective answer? Or am I missing something that invalidates this theory?

    3.) I don't want to derail the thread, but the other bullet that would supposedly work are the Lehigh Xtreme Defenders (what a name...). I used the search function and came up with some conflicting comments. It seems highly contentious all over the net if they work or not, if the gel results are good but aren't replicated in actual tissue/organs, etc. Since we are talking here about launching them at 2000-2400fps, would that change anything?

    Thanks again, this form is such a wealth of knowledge .

  3. #13
    Site Supporter DocGKR's Avatar
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    1. Sorry, you can’t really separate out bullet construction, length, weight, etc… from the analysis. Assuming an expanding .355 projectile was engineered to perform optimally at a higher velocity, one would likely start to see increasing TC effects beyond 1600 fps and certainly by 2000 fps. But again, there are a lot of parameters at work; for example, we see a larger TC with most .44 Mag handgun projectiles than for .357 Mag projectiles, even when the .357 are going a bit faster. FWIW, 77 gr OTM yaws, hyper-expands, then fragments which is a different mechanism than a relatively stable expanding projectile which does not yaw--like most handgun JHP designs.

    2. An effective answer for what? As noted, many times when solid copper HP’s are driven beyond their design parameters, the expanded solid copper “petals” fold back over the shank or fracture off. But sure, a solid copper HP could work well, if designed correctly and operated within the correct velocity range. Beware, there can be more “empty space” between the expanded “petals” than on an expanded JHP bullet. Also, make sure the RD measurements are done correctly, many I’ve seen on the internet are done improperly: https://pistol-forum.com/showthread....5136#post75136. Oh, for that matter, it seems a lot of hobby gel shooters incorrectly describe the TC as the PC, based on what I am seeing on YouTube (ex. https://www.youtube.com/watch?v=sBSl7CDkMNA)…

    3. The Lehigh Xtreme Defenders are a solid projectile that act like most FMJ handgun projectiles with a yawing effect. With higher velocity the TC will be a bit larger as the solid bullet yaws, but because a handgun projectile is generally much shorter than a rifle bullet, the TC is typically smaller than for an equivalent weight rifle bullet.
    Last edited by DocGKR; 02-03-2019 at 01:33 AM.
    Facts matter...Feelings Can Lie

  4. #14

    https://pistol-forum.com/showthread.php?29829-High(er)-Velocity-380-Bullets-in-a-9mm-

    Quote Originally Posted by StanBan87 View Post
    For these particular pistol bullets specifically, it does seem that limits you to the solid-copper and similar HP designs like the Barnes TACXP. At least at 1550fps the 80gr TACXP still seems to be meeting the FBI spec as well.
    I messed with some 80gr copper HP's loaded to higher-than-designed velocities. I wasn't quite able to get to the 12" mark in gel. Soft recoil, however. Such a load might be of consideration to someone who's overly sensitive about recoil.



    https://pistol-forum.com/showthread....m-Do-They-Work

  5. #15
    Thanks Doc, really informative post as always .

    One last question, what is the ~temp cavitation wounding velocity needed for things like the 62gr bonded bullets (like the Fusions) in 5.56? They expand to pretty low velocities, so I'm curious if their impact velocity was low enough they much still expand OK but be going slow enough not to induce temp cavitation wounding.

  6. #16
    Some threads from m4c.net readers here might find interesting on similar topics, while not completely relevant to the original question asked

    https://www.m4carbine.net/showthread...-Fragmentation

    https://www.m4carbine.net/showthread...s-Wound-Trauma

    https://www.m4carbine.net/showthread...levant-anymore

    https://www.m4carbine.net/showthread...-the-carbine-*


    Every Issue of IWBA Wound Ballistics Review Available Online
    https://drive.google.com/drive/folde...3pWYVVJeGlGaFE

  7. #17
    Quote Originally Posted by Sensei View Post
    The force is strong with you.

    There is very little reason to choose a PCC.

    A 8-9” barreled 300blk or 6.8 SPC PDW is within 2” of a MP5K in terms of size and has vastly superior terminal performance through every intermediate barrier...

    A 10-11” 556 is within 2” of an MP5N and will eat its lunch if fed RA556B or some other barrier blind load.

    I have a bunch of PCCs only for nostalgia and because the Mrs. likes them.
    Old school might work too--buckshot, slugs and 30-30's (and for real old school, .351 Winchesters). Its hard to send as much lead downrange with them . . . but then you might not need to send as much lead downrange.

  8. #18
    Site Supporter DocGKR's Avatar
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    Don't forget old school USGI M1 carbines w/quality expanding ammunition--they are far more terminally effective than a PCC.
    Facts matter...Feelings Can Lie

  9. #19
    Quote Originally Posted by DocGKR View Post
    Don't forget old school USGI M1 carbines w/quality expanding ammunition--they are far more terminally effective than a PCC.
    Absolutely--if you can keep the gas piston functioning in them (my luck has only been so-so with that--some of those carbines are seeing their last days). I think a .357 carbine is also more effective than a normal PCC. You can get a good 158 grain soft point round going 1800 fps, though you are limited to lever action.
    Last edited by Jeep; 02-22-2019 at 09:07 AM.

  10. #20
    THE THIRST MUTILATOR Nephrology's Avatar
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    Quote Originally Posted by DocGKR View Post
    This violent perpetrator took 27 hits of 115 gr JHP at around 1400 fps during an active shooter incident--too much expansion and too little penetration resulted in poor incapacitation effects.

    Attachment 34844
    That's an amazing plain film. Do you mind sharing more info about this event?

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