A couple of observations: 1) Maybe, just maybe Oswald practiced just a bit after he got out of the Marines. People act like he was this crappy shot and never picked up a rifle again until the day of the assassination 2)Connally was sitting much closer to the center of the front seat which makes the magic bullet theory less plausible. The shot makes almost a straight line through Kennedy into Connally when this is taken into account. 3) Kennedy's head moves backwards, but even if the "frontal shot" didn't happen, the acceleration of the car would have made him slump back anyway. 4) They have done studies that the head WOULD have moved backwards from a rear shot because of the momentum of the brain material being blasted forward 5) I've been to the grassy knoll and even though it was a train yard in 1963, the shooter would have been a sitting duck, completely exposed and very easily caught when he tried to make a getaway. 6) Dealy Plaza is a very cavernous space, surrounded by buildings. There would have been so many echoes that it would seem as if shots were coming from every which way. 7) Oswald had a motive. He was known as a Communist and JFK was very anti-communist (I know, imagine a pro-American democrat). What a grand way to strike a blow for his comrades. I used to believe in this conspiracy nonsense, but it's just an exercise in mental masturbation.
Marina's account places Oswald on the front porch of their rented house in Dallas spending hours performing 'snap-in' dry firing runs before the attempt on Gen. Edwin Walker's life.
That's exactly a part of the USMC marksmanship training regimen for rifle familiarization. You do it over and over and over again until the bio-mechanical action becomes second nature.