Sunday, August 10, 2008

We Get Letters

"Can you explain more what you mean about saying how jello tests work with bullets shot into it...and why its such a bid deal about twelve inches minimum deep penetration..."

Certainly. I'll break it down using information from the Dean of the gello-junkies, Dr. Marvin Fackler.

The reason the FBI has determined that 12" is the minimum acceptable level of penetration isn't because they fear their agents coming across Son of Kong, but the fact that skin is involved in real world shooting, as well as biological barriers such as arms and hands and forearms, etc.

To punch through the average adult human skin, a projectile must be capable of penetrating at least 1" of ballistic gelatin. To exit, a more difficult task, the same projectile must be capable of penetrating at least 2" of ballistic gelatin.

So if you took a sideways shot and hit the target in the upper arm, the round is going to expend 3" of its maximum penetration just to go in then out. Factoring in a 4" thick arm, we've just lost 7" of the rounds maximum push. Then it has to re-enter the skin of the torso, another inch off the max, so that leaves 4" to reach something most mortal.

If firing at a target from the front, often times the biological barriers can deflect or otherwise hinder a bullet from getting in unscathed. But at the end of the day its nothing more than a good guesstimate with some built in fudge factoring.

And remember; ballistic gelatin is standardized via the introduction of a BB fired at approximately 540 fps, and how many times have you seen a BB-Gun punch 3-4 inches deep into a human arm or leg?

Skin and clothing make a big difference in the real world and gelatin testing only factors in the meat of the matter. Sure, medium to heavy denim and toweling is also employed to simulate clothings, but the bullet is still penetrating a simulacrum of a simulacrum, something resembling the hog meat that resembles human meat.

People are also made of bone and gristle and have a tendency to move while being shot at, while ballistic gelatin sits there a'quivering without moving a single simulated muscle.

Gelatin provides somewhat repeatable examples of what happens to a bullet under somewhat controlled conditions.

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