Zapruder had a view behind the fence of the grassy knoll and saw nothing. Same with his secretary. And his film showed nothing there. Shots echoed? How is that happening with a suppressor? And bullet fragments found inside the front windshield have the same metal content as the box of bullets left behind by Oswald in the sniper’s perch.
I didn’t say a suppressor was used but one could have been, despite multiple people pointing to the Grassy Knoll, between the time of the fatal shot to Kennedy’s head and any view from Zapruder’s film was more than enough time to drop down and depart and it’s entirely possible all potential assassins were using the same ammunition
The point is for every possible reason you use I can point out something to counter it, but you take the word of a government that routinely lies about everything