MadScientist - you are probably flagged already for mentioning it here.
I was seriously interested in one some time ago but the LEO where I live won't sign for one and that is a requirement. I've had my CCW for 4 years now but still they won't sign. And you have to pay a $200 "tax" to the BATF for registering the thing.
As was stated above, if you shoot sub-sonics or shorts in a bolt action it is about silenced. When I shoot CB caps in my Remington Target Master the sound of the round hitting the target overpowers the sound of the shot. It's fun and accurate.