Debunking the "Jet Effect"?

[Andrew Mason]

Just for laughs - Andrew, do you think the image above shows matter being expelled out of the front of JFK's head?.

From the front half of his head?  Yes.
From the front surface of the head?  No

What matters is the direction of the matter exploding from the head exit wound at the moment it separates from the body. That matter spewed over a wide area that included the inside the car, on either side of the car, on the windshield and over onto the hood of the limo. 

The resulting kick from that explosive ejection of that matter will be equal in magnitude and opposite in direction to the vector sum of the momenta of all ejected particles at the moment they separated from the body.

[Dan O'meara]

From the front half of his head?  Yes.
From the front surface of the head?  No

What matters is the direction of the matter exploding from the head exit wound at the moment it separates from the body. That matter spewed over a wide area that included the inside the car, on either side of the car, on the windshield and over onto the hood of the limo. 

The resulting kick from that explosive ejection of that matter will be equal in magnitude and opposite in direction to the vector sum of the momenta of all ejected particles at the moment they separated from the body.

Form the front surface of the head?

??
??
??
I'm not even going to ask what this means.
So, just to be clear, you're saying the expulsion of matter highlighted below is coming from the front half of JFK's head.
It's a yes/no thing.