Wally..I think because they screwed that one up also. You see..three shells were not really necessary for three shots.
Though three shots were officially fired, it could have been be presumed that there were let's say 4 bullets loaded so BANG eject one shell...BANG eject a shell...BANG ...Ahhh job accomplished no need to eject ..no one need know about the brass that wasn't ejected.
The alternative was that the third shell was ejected in anticipation of the final shot but the target had then vanished..but that was not [officially] ever mentioned was it?
Who dug that report up?
It must have been in the Dallas Library archives somewhere and it got released- ooops
It is reflex action to eject he spent shell, and chamber a fresh cartridge after each shot....... And the Carcano was prepped to make it appear that two shots had been fired and the live round was in the rifle when it was found.
There definitely were more than three shots fired .....But some were fired from a silencer quipped weapon so most witnesses heard only three shots....
I believe the plot called for Lee Oswald and an accomplice to be framed but the man that had been set up as the accomplice had a rock solid alibi...so they were forced to twist the facts to make it appear that Lee Oswald was a "Lone Nut"