Yeah, you just have to put the silencer tube over the entire barrel and then drill holes down the barrel to bleed off the gasses. The holes serve to bleed off gasses both for the sound reduction and to slow the shot to subsonic speeds before it exits the barrel.

There are a few guys that have one, but don't expect it to sound like a mouse fart like on No Country For Old Men or something. There are some youtube videos of a guy in England with a few as well.