Here is a view of the grassy knoll from across the street from Zapruder's location. Note how compact the area is, yet somehow multiple riflemen were stationed in an area that is no more than 8-10 yards from where multiple people (including Zapruder) are standing. Also visible at the lower left of the picture is the infamous storm drain outlet along the curb. Anyone who could shoot upward from there and hit Kennedy and then pop out of the manhole and escape is a true Houdini.... :
Here's the view from atop the wall where Zapruder was standing, looking parallel to Elm St., towards the fence on the grassy knoll. The President was traveling left to right on Elm St. where highway sign is located. You can see the overpass where the President's car sped towards, after the shooting. Distance from Zapruder to the corner of the stockade fence is about 30 feet. Note that the fence forms a right angle along the edge of the parking lot it encloses, and that Zapruder could actually see the BACKSIDE of the fence that runs parallel to Elm Street, and had someone been there with a rifle, he could have seen them. Had they been on his side of the fence, he would have been greatly startled by the report of a high-powered rifle:
Here is the view from behind the stockade fence, looking down towards Elm St.. Note the high-deflection shot that a shooter would have to make to hit Kennedy:
Still standing behind the fence on the grassy knoll, this is what is directly behind you, the rail yard control tower. Note distance to the tower is about six rows of parked cars, or about 60 yards:
So, if you want to think there was more than one shooter inside the fishbowl that is Dealey Plaza, go ahead. Just make sure you visit the plaza for yourself and see how small it really is. In my mind, the issue is not how Oswald made the shot. I've qualified as a Master in NRA highpower rifle competition and having visited the plaza, I think the difficulties of the shot are not insumountable.
To me, the big question is: how did the parade route just happen to run right in front of Oswald's place of work, at a point where the motorcade slowed down to turn and where Oswald had unfettered access to a high building and an open window? The probability of LHO being able to make the shots is far greater than the probability that the parade route would be so conveniently placed. People seem to get hung up on the shot because most people can't shoot that well. I am more intrigued on who set the parade route right in front of Oswald. Coincidence? Maybe so, but the probability of the route being put there randomly is much less than the probability of LHO making the shot. A conspiracy hunt should start with who picked the parade route.....