I was the all comers champion shooter for our gun club the only time I competed, I didn’t win the prize because I neglected to list four hits on steel turkeys and after cards were turned in they could not be altered. But I did have the most hits and by three.
I think I could have made the shot but it is not by any means easy, and any one who says it is, is either lying, fooling himself, or a superior shot. One thing which stuck in my mind was when the FBI was testing the rifle, they discovered the scope was not zeroed very well. If he hit it was by luck. Of course that doesn’t mean he didn’t do it. I think he did but it was sheer luck.
By now, so many people have duplicated the actual shots fired by LHO, with the same cheap-o equipment, that your proposition simply doesn't hold water. Superior shot needed? Well, a good shot, anyway. AS always, good luck certainly is no handicap.
In re the FBI testing Oswald's rifle: in the time elapsed between the deed and the test, having been in police custody, and having been handled (or even mis-handled) by all and sundry, it is no surprise that a low-end scope would need to be re-zeroed. However, in their conclusions, the FBI allowed as how the LHO-single shooter theory was quite plausible.
Speaking of 6.5mm, I still own a 6.5X 55 Swede, which, a bit hotter than the 6.5 X 52, and the 6.5 X 54 and uses spitzer bullets rather than round-nosers, is a 200m "tack-driver" on the range without a scope. Very easy recoil, very easy target re-acquisition. The next step in combat rifles for the USA may well involve a 6.5 or 6.8 MM configuration. The Dutch, The Greeks, The Italians, The Swedes, The Norwegians, all came up with the 6.5 MM as their military answer to the range, penetration, lethality, accuracy compromise. BTW. The penetration achievable with a long, slim 6.5mm FMJ can be quite something, sometimes blowing through a whitetail and coming out the other side ... or close to it ... looking pretty good. I for one, have never had that much of a problem with the "Magic Bullet," especially since new research shows how Connally and JFK were lined up when struck.
I am reasonably satisfied that LHO was the sole shooter. The real question is who directed him. Again, I vote Fidel... who coopted the Mob ... and who had KGB help.