I had the brake and the parkarizing done at the same time. It was done by David Righter at Lacombe Gunsmith and Machine (on Web). The cost for everything was...you just need to call him. (985-882-7030) Tell him you saw Mark's slug gun that he just did and he'll know what you're talking about.
I did pay pretty good for it. It took alot of time. It is a screw on brake. As for the other details, I just finished it yesterday, so I haven't shot it yet.