Correct. He would also have heard the echo of the rifle blast from the hard surfaces around the plaza particularly the pergola to his right and the overpass ahead. Even the sound bouncing from the buildings on his far left would have reached his ears as part of a wall of sound arriving so close together it would have been impossible to distinguish their order. I doubt Hill would have heard the impact on the skull if he'd not moved much closer to the POTUS. That sound would have been lost in the cacophony of the other sounds. It was his closeness to Kennedy that made the combined head impact and rifle blast sound different and distinguishable creating a 'new' sound different from an earlier shot(s).
I think people sometimes forget that the witnesses only got one chance to absorb what their senses detected. We can read books over and over trying to pry open hidden secrets but Hill and others had just one chance. Everything else is hindsight to them.
The point is:.... Even though Clint Hill mentioned a revolver there is no way that he could know that the sounds he heard were the result of a revolver shot. He may have guessed right, but it was still just a guess, and he was comparing the sounds to some sounds that he had heard previously and he knew that those sounds were created by a revolver.
Bottom line....A bullet impact bang is the same whether it is fired from a rifle or a revolver.
