Warren commission determined that there was no way Oswald could have fired more than three shots. They also determined that two were fully accounted for: kill shot and the one that hit the curb. The curb one was determined by audio evidence as well as the fact that something hit the curb so hard it broke off a sizable piece of concrete so hard it hit someone several yards away causing an injury. While it wasn't 100%, there was no bullet found, that was the Warren consensus. There was never really any realistic argument against a shot hitting the curb but it isn't 100%, more likely like 95%. But it was considered a given by the commission. So much so that if you argue that this was NOT a shot, you really have to throw out the entire Warren Commission finding because that was considered a fact the entire scenario was built around.
That left one bullet of the three. And that is the magic bullet that hit Kennedy in the neck, went through the seat, hit connely shattering a rib, hit his wrist breaking a bone, and then lodging in his thigh. It then fell out on the stretcher. And it was almost pristine, meaning it was almost impossible that this bullet could have done all that and sustained almost zero damage. This has always been the crux of the argument stating there had to be a second shooter. The only way around it is to determine what hit the curb, if not a bullet. Or, how in the hell could Oswald have gotten off four shots and still only left 3 cartridges on the floor of the building?
In the end, the entire house of cards is built on three shots which leads to the magic bullet.
If the bullet was on the top of the back seat of the car, it could not be the magic bullet as there is an entrance wound to connoly's thigh but no exit.
Bottom line is if there were more than three shots, it almost certainly means two or more shooters.
