Here’s a quick Q&A type thing:
On shows like CSI when they shoot a gun into a tank of water to retrieve a bullet for comparisson to another one… Is the water just plain ol’ water? Or is it some kind of Fancy Water, or some denser liquid?
Always wondered about that.
Nope, just plain ol’ water. Water is dense enough to slow even high-velocity rounds to nothing in just a few feet.
Hm. Cool, thanks.
The way they film it makes the water look as thick as molasses.
Dense isn’t really the word I wanted here. Viscous would be better here, in the interest of accuracy.
There is a gel that forensic scientists use when they want to see the effect a bullet would have on human flesh. It’s designed to be the same density and viscosity and whatnot as human flesh, so shooting into it allows them to look at things like the size of the entry and exit wounds, the distance the bullet travels, and so on.
Yep, it’s called ballistics gelatin. They’ve used it on Mythbusters to test the effects of various projectiles on the human body. It’s basically a more specially-formulated version of the same kind of gelatin that Jell-O is made of.
Does it come in fruity flavors?
pictures guys in lab coats eating the “body” they made out fo jello…
Compared to air or compared to water?
I’ve always been curious how long a ballistic trap is required for rifle bullets. A spitzer (taperd point with a slightly convex curve called an ogive) boat tail (tapered to a blunt end) bullet is very aerodynamic compared to a pistol bullet and moving along at up to mach 2.5 or maybe more when it leaves the barrel so it will take more water to stop.
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The .50 BMG seems to be the worst case.
Am I correct in thinking that this stuff, unlike water, will deform the bullet like a real body does? AIUI the purpose of the water tanks isn’t solely to slow the bullet, but to do so without adding any extraneous marks to the bullet allowing the technicians to compare marks that actually came from the gun, and exclude those that didn’t come from that source.
Water can deform bullets in a similar manner to flesh, particularly unjacketed and hollowpoint rounds - see mks57’s link above. I’m pretty sure ballistic technicians use special low-velocity loads for test-firing soft rounds in the water tank to avoid this problem. But yes, the ballistics gelatin will have a similar effect on the bullets as human flesh. More importantly, the bullets will affect the gel in the same way they do flesh, which is the main point of the stuff.
Yes, and yes. Ballistic gelatin will deform bullets, expand hollowpoints and generally do as good a job of imitating the inhomogenous human body as a homogeneous medium can do. Which isn’t that great, as it happens, but it’s better than nothing.
The water tank has long been the standard method of obtaining undamaged bullets for direct comparison of rifling marks.
Re: On TV it looking as thick as molasses…
Compared to water. On TV the water somehow looks “thicker.” I suspect it’s just an optical illusion from it being a bit in slow motion (kind like when you see the camera from the point of view of the bullet piercing through organs – it’s happening a lot slower than at “speeding bullet” speed).
The bubbles in the water look too slow for regular water. Makes the whole shot look “syrupy”.
If I’m not mistaken, the ballistic tank shots in the various flavours of CSI are done with 3D animation software, rather than stroboscopic slo-mo photography. The bubbles you’re seeing are particle effects – it shouldn’t be surprising that it doesn’t look quite like normal water.
That would explain it. But you can see how I’d be confused “Er… is that supposed to accurately look like a bullet travelling at some true speed through some fancy liquid? Or is it just an eff-- Oo-oo-oo! Pretty!”