Hard evidence is physical evidence.
Witness statements are not hard evidence. Some are more credible than others.
Mortal Error (Donahue & Menninger)($30) & JFK The Smoking Gun (McLaren)($30) have a good analysis of witnesses re Hickey & re the AR15.
One bit of hard contra-evidence can falsify my theory.
A picture, a footage, a dent in the chrome, an exploding head, the smell of gunpowder etc etc --- hard evidence.
Provide a single piece of hard evidence that an invisible unicorn didn't take the head shot.
The fact of the matter is you can't.
You're whole theory is built on the fact that there was no picture taken that can refute it.
And that's all there is to it.
Of course you can't provide a sensible/rational/credible explanation for why nobody in the follow-up car saw or heard the AR-15 firing.
The sensible/rational/credible explanation is that no such shots were taken.
Of course you can't provide a sensible/rational/credible explanation for why over 20 witnesses on either side of the limo at the time of the head shot never saw or heard the AR-15 firing.
The sensible/rational/credible explanation is that no such shots were fired.
Remember this - you cannot provide hard evidence that an invisible unicorn didn't take the head shot.
That's the level you are working at. That's how credible your theory is.
Your theory suffers from a complete absence of Common Sense.