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Large caliber magnum rounds and hydrostatic shock

Discussion in 'Handguns: Revolvers' started by MTMilitiaman, Oct 1, 2019.

  1. MTMilitiaman

    MTMilitiaman Member

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    In the study of terminal ballistics, it is a commonly held belief, established through laboratory testing and actual field/service use, that there is a lower velocity threshold for hydrostatic shock damage in tissue. This velocity threshold is typically held around 2000 to 2200 fps.

    Hydrostatic shock refers to the pressurized shock wave that travels away from the projectile when it encounters a liquid or semi-liquid solid. While these forces exist at lower velocity impacts, most living tissue is elastic and fairly resistant to these forces under a certain projectile impact velocity. Tissue will be displaced but will stretch and rebound with little or no damage. However, above about 2000 to 2200 fps, we see that these hydrostatic shock forces become too fast and too violent for elasticity of the tissue. The tissue will be stretched beyond its breaking point and will tear, causing potentially massive amounts of damage well beyond the actual trajectory of the projectile. So typically, when dealing with common service handgun rounds like the .45 ACP, energy plays very little role in incapacitation. Rather, all that matters is diameter and penetration, because only the permanent crush cavity, that tissue actually crushed and physically displaced by the projectile, will remain; there is no hydrostatic shock damage. So your wound channel is typically a fraction of an inch in diameter, usually about 80% of the diameter of the projectile when it penetrates, because again, tissue is elastic. At the same time, even a small caliber, high velocity rifle round is capable of doing several orders of magnitude more damage than any service handgun. The high velocity of a rifle round like the 5.56 causes cavitation damage often a couple inches from the trajectory of the round. So even an anemic high velocity rifle round is capable of doing 2 to 3 times the damage of any service caliber round.

    Obviously, however, we can not speak in absolutes about something for which there are so many variables. Gel testing is one thing, but actual street and field results are quite another. In gel testing, we can see that nose profile, the degree and speed of a projectile's expansion, and other factors are important. In the field, we see that organ density, shot presentation, and the complexity of living bodies makes conjecture dubious and speaking in absolutes foolish.

    I have seen pictures and heard first hand accounts of large caliber magnum handgun and rifle rounds operating below 2000 fps but still apparently capable of doing some hydrostatic shock damage. Rounds like the .45-70 and the .500 S&W seem to be capable of producing cavitation damage beyond the trajectory of the round, regardless of the fact that they are operating several hundred feet per second below commonly held velocity thresholds.

    So what role does caliber and nose profile play in the creation of hydrostatic shock? Is there an established relationship between the caliber of a round and what velocity is necessary to create cavitation damage in tissue? To what degree have handgun hunters and those hunting with large bore rifles witnessed this phenomenon?
     
  2. JeffG

    JeffG Member

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    I have seen the effect when shooting .458 cast bullets with wide meplats in the velocity range of 1600-1700fps. There seems to be a duality of performance. Striking bones creates a "broken china" effect, the shoulder or leg bones break into several pieces, inches away from the bullet path, like you would see with bowling pins ricocheting off one another. Line of sight penetration is usually maintained after striking bone.
    On soft tissue with ribcage shots, the skin, subcutaneous tissue, and muscle show little sign of bloodshot, or temporary wound channel "hydrostatic shock" damage. When the bullet continues, and enters the organs of the chest, the tissue definitely wants to "get out of the way" of the flat bullet, and more shock wave damage is evident in connective tissue, aorta, liver, lungs etc. Probably due to the pressure waves moving off of the bullet nose at near right angles. I don't have extensive experience, but this is what I have seen.
     
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  3. MTMilitiaman

    MTMilitiaman Member

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    Interesting. So striking a bone or other prominent, high density tissue with a wide, flat meplat seems to be the deciding factor? The only time I saw this was a .45-70 to the shoulder, which was very destructive for a couple inches from the path of the bullet.
     
  4. JeffG

    JeffG Member

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    It seems the bullets weren't going fast enough to breeze through, but more like breaking a chair leg with a hammer. Fragmentation was up to 3 inches from impact. Which was weird, because through muscle, you'd swear you could "eat up to the bullet hole", as the cliche' goes. My hunting partner saw the hide "ripple" through binoculars. In the chest cavity, destruction was more pronounced, whole lungs were bloodshot, if the liver was hit, it was pulped, not just a hole. This was on bison, watusi, hogs and yak.

    Here are the rounds I shoot.
    IMG_2604.JPG
     
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  5. MaxP

    MaxP Member

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    Jeff, I think they were going plenty fast to exit. The problem is the bullet material. Cast bullets cannot stand up to velocities a .45/70 rifle is capable of generating. Once the nose gets wiped off, all bets are off. We have experienced a significant amount of failures at lower velocities testing on bovines. A monolithic solid would have most likely exited.
     
  6. buck460XVR

    buck460XVR Member

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    While caliber, profile and type of projectile, from a straight walled handgun caliber, fired from a revolver, can and does contribute to the wound channel, It does little or nothing for hydrostaitc shock, since there is little or no hydrostatic shock produced at those velocities.....especially at the velocities produced from even the biggest magnum revolver, by the heavier projectiles used for hunting.

    JMTCs.
     
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  7. The Evangelist Cowboy

    The Evangelist Cowboy Member

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    I can't quite contribute to this conversation in a great way, I do however remember In Paul Kirchner's Book in which Jim Cirillo had to explain to med students and paramedics the effects of a shotgun slug to the head of a perp, they didn't consider the effect of hydrostatic shock when looking at the wound. A shotgun slug is alot slower moving and weighs much more than the typical rifle or pistol round, I trust Cirillos experience as he probably has more police combat experience than anyone post 1880s.
     
  8. WrongHanded
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    WrongHanded Contributing Member

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  9. labnoti

    labnoti Member

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    5.56x45mm vs. .458 SOCOM. Both have sufficient penetration for their intended target. The 5.56 clearly meets the propositional velocity threshold for "hydrostatic shock." The .458 was specifically developed for faster incapacitation with fewer shots, but it is clearly below the velocity threshold, esp. with heavier bullets. What is the real result?
     
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  10. Apuesto

    Apuesto member

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    I have noticed over the years that large caliber bullets seem to produce a "shock" (or a flinch?) even when going at a fairly moderate pace which I don't see with smaller calibers or bows. It's not the same as a high velocity rifle round as the damage around the wound channel isn't nearly the same.
     
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  11. Tradmark

    Tradmark Member

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    Any damage larger than the size of the bullet is hydrostatic shock. Noticeable difference in game animals as far as wound channel goes with the same bullet as velocity goes up as long as the bullet handles the impact.
     
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  12. SDGlock23

    SDGlock23 Member

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    Typically with big bore handguns many hunters will opt for a very large meplat, which is how wide the flat nose of the bullet is and even at moderate velocity they can produce a large wound cavity. I wouldn't worry about how much hyrdrostatic shock there is or isn't, big bullets just hit harder than small ones.
     
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  13. Tradmark

    Tradmark Member

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    If you a big 50 cal hardcast at a sedate velocity around 1100 fps makes a bigger hole and damage than a 45 cal going 800-900 fps faster i would suggest to shoot more stuff and check wound channels. That same 50 cal bullet in solid copper instead of lead will make a bigger wound channel at 1400 fps and bigger yet at 1600 fps and even larger yet at 1800 fps and so on and so on well below a threshold of 2000 fps.
     
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  14. 35 Whelen

    35 Whelen Member

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    I showed this picture in another thread last week, but it fits perfectly with the subject matter here.

    ~250 gr. .430" SWC fired from a 4 3/4" SA .44 Special. MV was a smidge under 950 fps and the bullet struck a buck some 50 yds. or so away low in the right shoulder, creased the heart, through the off side ribcage, exiting for parts unknown.

    buckshoulder-1_zpscbe93d7f.jpg

    Despite the relatively low velocity and small meplat (~.300"), there obviously was lots of damage, as evidenced by the bloodshot meat. Here's what the heart looked like. Notice the wound track is larger than the diameter of the bullet. (Sorry about the crappy pictures. All I had at the time was a flip phone)

    Buttonbuckheart-1_zps9caf9815.jpg

    I shot a sow with the exact same revolver, bullet and load as she stood broadside 44 long paces away. I hit her in the shoulder and the bullet made a huge mess inside.

    Another pretty amazing one. This is from an RCBS 44-250KT mould, cast of air-cooled wheelweights (Bhn 13+/-). It struck a buck behind the last rib on the left side at a velocity of about 1050 fps, travelled to the juncture of the neck and right shoulder where it stopped under the skin. As one can see, it smacked a bone somewhere along the way, yet tracked nice and straight.

    44-250KT4_zps7228710d.jpg

    44-250KT2_zpsd9b41e59.jpg

    Now to illustrate the opposite, this blue quail was shot with the same revolver, only the load was a 255 gr. cast RN bullet running around 775 fps, and the bird was about 20 yds. out.

    Revolver%20and%20Quail_zpsx7hxkw3l.jpg

    It struck the bird just behind the right wing root and I had to part the feathers to see the bullets entrance hole.

    35W
     
  15. JeeperCreeper

    JeeperCreeper Member

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    With so many variables from target construction to bullet construction... I try to keep it simple most days, and only complicate it on bored days.

    With big and heavy, I look at energy.
    With small and fast, I look at velocity.
    If it's in the middle, I look at both.

    But.... I'm no expert and I'm here in this thread to be learned.
     
  16. buck460XVR

    buck460XVR Member

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    That is not my experience. I hunt deer with revolvers and carbines in both .357 and .44. Velocities from the carbines are significantly higher than those from my revolvers. Yet, when I butcher and process the deer shot with both platforms, I see little or no difference from the wound channels when using the same bullet. While I do see more damage to bone from the higher velocity rounds, this is caused by temporary cavity effects.
     
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  17. MaxP

    MaxP Member

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    Energy calculations favor velocity. Energy in an of itself is a poor measure of lethality.

    To over simplify, if your bullet is up to the task, velocity is your huckleberry. More damage will be the result versus lower velocity. I download nothing.
     
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  18. Tradmark

    Tradmark Member

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    What bullets are you using. I would be curious to know because my son shot 7 deer with a 41 carbine, i had always been told the same, and the wound channels were massive. By far bigger than anything shot with a 480 or hardcast 475. Then again we used swift aframes.
     
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  19. JeffG

    JeffG Member

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    I wasn't clear, they all went through and through.
     
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  20. buck460XVR

    buck460XVR Member

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    As I said before,
    When one goes to Swift's website and look at their A-Frame revolver bullets you see this...
    So yes, they should produce an effective wound channel, due to their expansion and dump of energy. But that is not an example of Hydrostaic shock, even at .41 carbine velocities.....and this topic is not in the rifle forum, but revolver. Massive is a subjective term and if those A-Frame do indeed expand as per the Swift website, their diameter at exit would be .65, far larger than a non-expanding .480 projectile.

    Wound channel damage most of the time is caused by direct shock from impact, penetration and passage of the bullet itself. This is true not only for revolver ammo, but even the fastest rifle ammo, when one is talking medium to large game. Hydrostatic shock if there, can be the frosting on the cake, but I wouldn't depend on it.
     
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  21. Tradmark

    Tradmark Member

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    Well since my fa83 uses a load the same velocity as factory rounds out of the lever gun it applies here! I have wound necropsy pics where an entire lobe of the lung of deer are destroyed. Wound channel is in inches not decimals. Much much larger than the width if the expanded bullet. Once again, any wound larger than the caliber of the bullet is due to hydrostatic shock. End of story. If you didnt see it i suggest you use better bullets.
     
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  22. dickydalton

    dickydalton Member

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    I know one thing for sure. About 17 years ago I shot a deer at 166 yards with my Model 629 S&W 44 Mag. 6" with a Leupold 2XEER on it. The Bullet was a 300 Hornady XTP Hollow Point loaded to 1250 FPS if I remember right. The deer ran about 20 yards and dropped. When we dressed it out the hole in was the same size as the hole out, one rib broken going in and two on the way out. The bullet center-punched the heart and I could put my pinky finger in the hole. That bullet didn't expand at all and it kept on going.
     
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  23. robhof

    robhof Member

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    I use a wide flat nose in my 357 Supermag and though smaller than the above rounds mentioned, I've had many deer kills with one shot drops, I'm using a 180 gr bullet running at 1600fps.
     
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  24. BWS

    BWS Member

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    I shoot a lot of varmints with cast bullets,both rifle and revolvers. Though,not shooting my revolvers near as much. Only thing I know for sure is...... the sharper,and "crisper" any leading edges of flat points and any drive bands,the better. It somewhat over shadows calibers. Meaning a real sharp edged 7mm will tear a crow or Ghog up more than a .30 with poor meplat definition. Velocity then enters the picture..... and it too makes a bigger difference than a slight increase in diameter. Sometimes dramatic,but that can be individual hit location. A really "crisp" cast, .22 out of a 223 or 22-250 with velocity over 2500fps using moderately hard alloys will blow a crow into several chunks..... we measure how far the pcs get slung as the metric.
     
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  25. GooseGestapo

    GooseGestapo Member

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    One thing I haven’t seen considered is the secondary projectile effect of hitting bone. Early previous poster came close when describing what he called a “porcelain china” effect.

    A bullet hitting bone causes secondary projectiles to impart additional damage, often far greater than that simply imparted by the primary projectile itself. If you’ve ever seen a ~200lb deer hit in the neck by a 140gr bullet from a 7mmMag at ~3,000fps to the spine can envision what I’m describing. The exit wound will be several inches in diameter. It’s not cavitation in this instance. Cavitation is simply the mechanical “boiling” of a fluid by energy transmitted by an object. Like the bubbles in the water from the passage of a boat propellor. Shock wave damage is like the boat wake, but tissue being elastic can absorb it somewhat (temporary wound cavity). It’s the dozens of bone shards like tiny razor blades shredding tissue as it passes. ie: shrapnel.

    Hence, a large meplat will displace more media than a small meplat. Simple physics. Higher velocity creates greater inertia, a different expression of energy than kinetic energy. Both factor into terminal performance.

    So, a large, blount bullet traveling at a high velocity will impart more terminal effect than a smaller one. And as stated, the bullet’s integrity to avoid deformation factors too.
    Hence, as we already know, a large, heavy blount bullet at a modest velocity has a well known behavior, as well as a small, light bullet going 2-3x the velocity of heavy bullet exhibits a different type performance.
    Therefore, the century’s old “caliber wars”.
    If you’re going to sink a ship, use a CANNON. If you’re going to kill an elephant, use a .375-.600” rifle. If you’re going to shoot squirrels, use a .22rf.
    Like Capstick said, use enough gun...
    But we also have to consider “fads”, and “political correctness” too...
     
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