I believe the Discovery Channel special was "Inside the Target Car"? But they only simulated the/a head shot not the back shot. Unless you're thinking of another one? I too vaguely recall another special in addition to the NOVA show duplicating something you mentioned with #399. Either both of us are losing it or neither one of us is. Let's agree to go with the latter explanation.
That "Target Car" can be viewed here: https://archive.org/details/JFKInsideTheTargetCar
You may be thinking of the November 2004 Discovery Channel episode of "Unsolved History" called "JFK: Beyond the Magic Bullet". The same program gave us "JFK: Death in Dealey Plaza" (2003; timeline of the photographers), "Robert F. Kennedy Assassination" (2004), "JFK: The Conspiracy Myths" (2004) and "JFK: The Ruby Connection" (2005). One site lists "JFK: Inside the Target Car" as part of the "Unsolved History" series but that show came out in 2008, after the series ended.
See David Von Pein's review of "JFK: Beyond the Magic Bullet" (
Link ). "The closest we're likely to ever get to a perfect duplication of the Single-Bullet Theory".
The rifleman didn't have the luxury of a large target. He was on a lift exposed to wind and at a comparable distance. It's remarkable he came so close to where the "back wound" was.
The minor spread meant the bullet emerged from the simulated "body's" chest. Not a great concern as the "Kennedy" surrogate (unlike the "Connally" surrogate) had no hard tissue embedded in it. Unfortunately, critics expect some mirco-level precision with living models.
There was a test done by Failure Analysis Associates for the ABA Convention's August 1992 "mock trial" of Oswald, in which a short-loaded Carcano bullet was used. They fired a Carcano bullet with a lowered velocity of 1100 feet-per-second into a cadaver's wrist. Why weaken the velocity?
Dr. Michael Baden said: "That bullet [CE399] slowed in velocity each time it traversed another body part. there was a debate on our panel as to whether the bullet even hit Connally's rib or just passed close enough to do the damage. But most of of us thought it hit the rib while tumbling, and a sideways hit explains why such a hard bullet is flattened. When it struck the wrist bone, which is small, it was not deformed, since its velocity was so low. By time it left the wrist, its speed was greatly reduced, and the nature of his thigh wound shows it was a spent bullet by then."
This context is important but usually ignored by CTs. Dr. Martin Fackler, then president of the International Wound Ballistics Association, participated in the FAA weak-round tests. He said: "The bullet actually made a slightly greater hole than the one in Governor's Connally's wrist. That's because the experiment bullet was actually going a little faster than the 900 feet that CE 399 was traveling. the test bullet was non-deformed. It was not flattened in the least and had nowhere near the damage of CE 399". Sorry, I don't have any more information of this test than this.
BTW, not much of a hole in Connally's radius bone. The bullet slapped off the bone and left behind a series of fractures that were reset in surgery. There were no bone grafts.