[Alpo]

Yes there is. You got me intrigued, so I went and found a fired (but still with the dead primer in it) 357 case and stuck it in an empty 357. When the hammer fell on the empty, the sound was not as loud. Slightly muffled. To make sure I wasn't imagining things, I spun the cylinder and closed it without looking, so I did not know where the empty case was, and then shot my way around the cylinder. I could tell by the sound when I hit the case. The empty chambers, in the cylinder, had a very slight echo-effect to them, while the fired case not only did not have the echo, but kinda sucked up the sound of the hammer falling.

I was doing that with a 2 1/2" barrel. Barrel length has a lot to do with the sound. Maybe with a six-inch barrel I might not have been able to hear the difference.

Either way, the sound difference is very slight, but it is there.