So I'm currently writing a steampunkish space western about an assassin who works for a twisted futuristic version of the Roman Catholic Church, and I'm doing some weaponstorming.
My MC carries around a pair of Whisperers, long-barreled revolvers that are designed to fire silently. But instead of having to screw a silencer on, the silencing mechanism is built into the firearm itself.
My problem is that I have no idea how that would work. I'm not really a gadget guy, and not the best with moving parts. 

 Does anybody out there have a notion of how I could do something like this?
The second thing is a grapple built into the character's mechanical arm. The grapple itself is shaped vaguely like a crucifix. It would be designed to fire from his wrist, lodge wherever he aimed it, and then let him reel himself up or rappel down. But again, I'm trying to figure out a feasible way to power and operate it.
Any thoughts?