where did Benevides ever say he saw a revolver?
Benavides said that he saw the killer remove a spent shell ( singular) from his gun and flip that spent shell away into the bushes....Do you believe that Benavides was referring to an automatic?? What else could Benavides have been referring to?, but a revolver....And a revolver that was NOT a Smith & Wesson.
IOW, he didn't say it was a revolver.
At least, I agree that he said he saw the gunman unload a
single round from the weapon. That could definitely be a revolver. However, it could also be a derringer. Or a single-shot. Or a pepperbox. And, it could also be someone manually clearing a jam from an automatic.