The Carcano is medium powered, not high powered. Where does it say that rifle-fired bullets will not "deflect" upward like that? Intact bullets will assume curved paths in ballistics gelatin. Deformed bullets will begin curving sooner and to a larger degree.
What ballistics tests show that such a round will deflect sharply upwards upon encountering one layer of skull bone? Here is the Tracking Oswald part 5 ballistics dummy test:

"Many of the fragments deposited in the president's brain were flushed out, along with the brain tissue, as the large amount of blood flowed out of the explosive wound in the head, in the car and at Parkland. It is evidently some of these that were deposited on the bone flaps by clotting blood that show as a "trail" of fragments near the top of the lateral view. This "trail" does not show on the frontal view, and is much higher than the FPP's reconstructed trajectory. In fact, at the apparent location of these fragments there was no brain matter in which the fragments could be embedded."- The JFK Myths: A Scientific Investigation of the Kennedy Assassination, By Larry Sturdivan, Page 201.
https://www.amazon.com/JFK-Myths-Scientific-Investigation-Assassination/dp/1557788472
What? No, fragments deposited at the base of the head could not have "leaked out" from a hole in the parietal bone.
Why should there be severe damage to the cerebellum?
Because severe damage to the cerebellum would be an inevitable obstacle for a straight-moving bullet. Do you think a 6.5 round deflected sharply upwards as soon as it got past a single layer of skull?
P.S. do you have a mobi file of JFK Myth to share?