"Ballistic" gelatin is fundamentally Knox (clear) gelatin, the same stuff used for jello, made to a very specific and controlled forumla. By controlling the preparation, we end up with a very consistent product interms of density, hardness, resiliance and other such factors. This means that ammo tests I conduct in my state will closely match those done by someone else, and this has always been the hard part.
In terms of "simulating so well" we'd have to spend a long time in discussion to fully answer that one.
the short answer is that Gelatin (in the ballistic mix) does a reasonable job of simulating the density and consistency of human MUSCLE. You'd be amazed how much cutting gelatin blocks feels like butchering meat.
However, NOTHING can simulate "the human body" in any effective manner since the density of the body changes constantly. Bone, muscle, soft tissue, "hard" organs, more bone, skin, etc. There's NOTHING consistent about the human body.
There are several other methods that do well, a "water box", various clays, wet newspaper or phone books and a new product called "Bullet Test Tube" (a wax like material).
BUT, the real search is for consistency from one test to the next. Gelatin has been in use for a good long time and has pretty much been accepted as the "standard".
geoffbeneze
http://www.beast-enterprises.com