There are two gaps between the three shots, about eight seconds each. Most CT adherents divide by three, which is a mistake. Oswald cycles the bolt twice, not three times.

Oswald was trained in the military to shoot and IIRC earned sharpshooter, so there's no reason to suspect that he could not have shot JFK.

Anyway, all the forensic evidence supports that he was the assassin, no matter how many more shooters were in Dallas that day. Both recovered bullets were shot from his gun.

Hope this helps.