As LHO's shooting ability has been called in to question, a little known fact is that he purchased the Carcarno and had it fitted with a scope, then he went to a shooting range and got a bloke there to zero the scope for him.

After doing that, the chap who zero'd the scope asked LHO to try it and he fired three shots scoring a bullseye at 100 yards with all three.

LHO was at the shooting range at least twice more after that so he'd had some practice with the gun before shooting JFK. The range from the book depository window to the position JFK was in at the head-shot was 265 FEET!

At that range and resting on the windowsill, I think even I could have made that shot with an ordinary .22 using only long rifle HV cartridges. It would have been much easier with the 6.5 m/m rifle and the ammo LHO used which had a greater powder charge. (That is, much greater than the charge in a .22 HVLR)