Compressed air trapped in the hollow cavity of SMK ??


Well-Known Member
May 14, 2003
During this deer season I saw heart-lung damage that seems impossible for the bullet itself to accomplish. I have a theory that is not yet well thought out that much of the damage might have been done by air compressed in the nose of the bullet and released as expansion began.

Am I completely out of left field? Of course, I do not have any idea the pressure the air is compressed to or the volume of air contained at whatever pressure is there. But.....A truck tire exploading somewhere before reaching 110 psi kills the maintance man. A SCUBA cylinder exploding somewhere before 3000 psi destroys a dive shop.
I think it'd be an issue of available volume... Insignificant for the cavity inside a MK I'd guess.
What kind of damage are you talking about? Bullets do some very strange things when they hit game.
yea, im with dave on ths one--dont think there is enough room there to save up much pressure.

you may have just taken a chunk of something (skin/bone) thru with the bullet causeing more damage or hit something before entering the animal (twig/grass)

Probably what you are seeing is the damage caused by "temporary cavitation". There are 2 things a bullet causes as it passes through flesh, 1: a wound chanel, and 2: cavitation. What that basically is, is like a shock wave in the flesh as the bullet passes through. It can actually tear meat and tissue of of bones.

When a bullet causes a 1/2" wound channel, depending on the density of the aniaml and the energy of the bullet, it will cause a 6-16" wound area cause by this cavitation.
The lungs were probably filled with air, if so their going to popp like a ballon, causing lots of damage, same with the heart if you hit that when its under presure, the heart explodes and so does most of the blood vessels causing causing even the toughest animals to drop instantly.

I have also found that when the lung/heart are hit and turned into jello and the bullet exits there is a vacume effect and some of this jello gets sucked out. One deer I took this fall at 93y with a 140g SST 270 win sucked almost all the lungs out. The far side of the deer and snow were a mess. The explosive affect of some bullets can make a huge internal mess also.

[ 01-30-2004: Message edited by: Harv ]
i think the main thing you're seeing is the second reason that meichele described. animals, like humans, are mainly made up of water. as a bullet hits and delivers a shock wave, the water acts as a medium for it to travel throughout the body. the most simple way to test this is with an aluminum can. take 2 out, but fill one completely with water, and shoot them with something small and slow- such as a 38spc. the empty one will just leave a hole. the one with water though will probably get shredded like a piece of paper. obviously a can is not going to let something like a semi-wadcutter expand at all, but its the shock wave that does the most damage. look at picture of a bomb going off. before the firey explosion hits anything, the white ringed shock wave gets to things first, and inflicts the initial damage. thats why i laugh at movies when guys go underwater to avoid explosions. ever see a fish smile when you bang on the side of a fishbowl? water acts as a medium to amplify waves of that type. when a bullet hits the body, the fluid in the body does the same thing.

I have seen what Harv mentioned, matter of fact we had a 168 gr. XLC bore along the spine of a mule deer and exit by the tail, and the entire wound channel was filled with hair that had to come in from the entrance location.

When I shoot clay I get a strange vortex looking cylinder inside the wound cavity that also would indicate that the clay materiall is being sucked in behind the bullet.

Terminal ballistics is a very interesting topic.
If I'm not mistaken, something else must be at work. How about the air mass that is being pushed aside behind the bullet. If the bullet is spinning wouldn't the air partually around it. Sort of like the Matrix when the bullets are causing that vapor trail??
air compresses, so I don't think the air around the bullet is doing much of anything with regard to damage. As stated earlier water does not, so a supersonic shockwave that passes through it stretches and tears tissue. One other thing I have noticed is the effect of a bullet on bone, creating a shower of high speed projectiles which can do significant damage on their own.
Harv and Ian; I've seen the same thing you are talking about. As you know we can have once in a life time hunt every year because of our moose and deer in our back yard. The Bullet Manufacturers I've talked to all say a velocity impact on the HIGH END of 1600-1850fps will give a quality expansion. IMPACT IS THE THE WORD and not at the Muzzle. My Lapua needs range, but a new bullet by Nosler in The Accubond seems to be doing it because of the thin jacket and high BC for down range.
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