I appreciate your feedback as a way to determine whether or not Donohue's theory is plausible, which is my ultimate prosecution. This is a summary of the events leading to the accidental shooting of President Kennedy according to Donohue, let me know what you think.
"According to Donahue’s analysis, the shooting unfolded like this: Oswald fired his first shot from a sixth-floor window of the Texas School Book Depository soon after the motorcade made the turn onto Elm Street. But his scope was not adjusted properly, according to the Warren Commission, and the bullet missed, hitting the pavement behind and to the right of Kennedy’s limousine. Fragments ricocheted up and struck the inside windshield trim. At least two caught the president in the scalp and caused him to cry out, “My God! I’m hit!”

Oswald chambered a second round. This time, he skipped the rifle’s offset-mounted scope and instead drew a bead along the iron sights on top of the barrel. He fired again and the bullet ripped into Kennedy’s upper back, exited his neck and pierced Gov. Connally’s right side.

At this moment, photos from Dealey Plaza show Secret Service Special Agent George W. Hickey Jr. — riding in the left-rear seat of the follow-up car and sitting up high near the trunk deck — already had turned completely around and was looking back toward the book depository. He may well have spotted the barrel of Oswald’s rifle protruding from the sixth-floor window.

So Hickey reached down and grabbed the Colt AR15 select-fire, semi-automatic rifle from the floor of the car and flipped the safety lever off. He started to stand and turn to acquire Oswald’s position and return fire. But the follow-up car braked suddenly to avoid a collision with the presidential limousine and Hickey lost his balance. His finger slipped off the trigger guard and the weapon discharged. The bullet was flying at 3,300 feet-per-second when it slammed into the back of Kennedy’s head, 21 feet away, and disintegrated."
https://mokan9997.medium.com/hidden-in-plain-sight-4761be7b8115