We continue coming back to the "ear witness" stuff. You can't have it both ways. You rely on the "ear" and you then have an issue with the time involved to physically work a bolt action rifle.
Roselle's and Scearce's study had nothing to do with what those seven witnesses said, but how they were caught on film physically reacting to the sounds of Oswald's first, missing-everything, shot.
Since that shot was at "Z-124" and the next one was at approximately Z-222, Oswald had approximately 5.35 seconds to "work the bolt" and recycle a round into the chamber for his second shot.