A couple of things to chew on. I remember an old CBS real crime program called TOP COPS IIRC. In one episode, a woman was accused of murder. She said that an assailant had shot her husband--the bullet passing through a window.

Shards of glass were found outside the window, on the grass. Cops initially suspected that she had shot her husband from inside, and the bullet travelled through him and hit the window, breaking it inside out.

They were wrong.

One cop shot at a replaced window at a certain angle, and the glass jumped right in his face--even though he was outside.

In the show MONSTER: A PORTRAIT OF STALIN IN BLOOD, we saw the excecutioner behind a prisoner standing in the near end of his own grave that he had just dug. The idea was that the bullet would hit him and he would just fall over like a wooden plank. He arced back from a muscle spasm and the gunmen all but dropped his pistol to catch the corpse as it collapsed about the knees. He pushed with all his might and he still fell into a ball.

The killer actually had to get in the grave with his victim to stretch him out.

Execution is a hard job comrade!

So things don't always work they way you'd think. If the 'other' gunman had been on the Grassy Knoll the exit wound would have been the other side of JFKs head.

I do seem to remember the Cronkite narrated NOVA special that spoke about the dictabell (dictabelt?) and it showed possible paths that lined up if the figures were sitting a certain way. One possible path led to the base of and to one side of the Schoolbook Depository--where no conspiracy theorist had ever made a claim.

If there was a second gunman--he'd have been there.

Look, you really don't need a magic bullet. With the way folks sat, a straight path looks snake-y if you replicate the scene with ramrod straight Buster dummies sitting in too good a posture. If I am bent over, a bullet shot down into me will look different if you plot the same path thru a sitting dummy. It will look like a midget shot from below and behind and the bullet 'rose' up.

Same here.

They also filled a skull full of gel and it lept backwards when hit.

Anyone who plays pool knows that you can hit a ball and make it go anywhere you want it by putting enough english into it.