Nobody that I know of in the south hunts deer with an empty chamber; it's simply unheard of and would be virtually impossible to get away with on whitetails in close quarters. Hell, I won't even hunt with a rifle with a noisy safety let alone have to work the bolt before I shoot. I believe the OP asked about actions other than semi-autos. I suspect that a single shot would be the quietest, but probably not the fastest. As another poster suggested, if you work the bolt right after the shot I doubt the animal will hear the sound of the bolt during the blast. That is what I do and have used a follow up a time or two to prevent an animal from running someplace I didn't want him to with a second shot or taking a second, third or fouth animal out of a crowd.
