Would not it have been quicker for the shooter to flip the drum/cylinder out, hold his thumb over the 2 unfired rounds, and shake out the 4 spent shells in his other hand all at once?
That seems to be what some witnesses describe as the shooter pointing the gun barrel up and shaking it.
So does the rebored size of the cylinder wells cause a problem of shells not sliding out even if shaking the gun with the barrel pointed up?
If so, then maybe it is plausible the shooter had to resort to having to pull out each shell one by one.
However, What is the reason for The carelessness , of the shooter, seemingly not worried about leaving fingerprints on that those shells he is removing one by one, and throwing them at the scene in LOS of witnesses?
It’s NOT because he was trying to be quick , that’s fairly evident by how long he lingered at the scene, (as Mr Iacolleti already pointed out.)
A few alternatives:
1. The shooter was the CIA/FBI informant Oswald in a state of confused mind, perhaps paranoid, and was not analyzing his situation rationally when confronted by Tippet.
2. The shooter was “the nut” Oswald and was in a state of mind in which he was euphoric and desired that his face should be seen and that he should be seen throwing shells at the scene.
3. The shooter was some person who resembled Oswald, and shot Tippet for no reason connected to Oswald or the JFK assassination.
4. The shooter was some person resembling Oswald who was part of a conspiracy to set up Oswald, thus throwing shells and lingering, and face seen, was meant to implicate Oswald.
In none of the above alternatives can a de facto conclusion be drawn that the shooter must have also been the JFK assassin.