I have a B-square on a stainless steel Blackhawk 357 Mag. I was hesitant at first, because I wanted to shoot heavy loads and was afraid the that lack of many drilled mounting screws would result in slipage. It hasn't.
The B-square I have has about 3 screws that "pinch" the front blade site and a rear screw that goes in the "adjustable rear site" screw hole. I didn't have to do any fitting, it fit just fine when I bought it. The only modification was to remove the rear site and put all the pices in a small plastic bag and put that bag in the gun safe, where hopefully I will be able to find it, if I ever want to go back to "as issued by Ruger" configuration.
Since I have two 357 Ruger Blackhawks, one in Stainless that I scoped and one in blue that I shoot as it came from the factory, I doubt that I will take the scope mount off anytime soon.
I do have to admit that the scope and scope mount do add a bunch of weight to the Blackhawk. It gets really heavy at the range after a few shots.
The B-Square mounts can be found on the internet for less than the "manufacturers suggested retail price is." At first I didn't but a scope mount because of the price. Eventually, I saw one on saw and dove in. It is pretty awsome, but finding a holster to handle a scoped pistol (that you like) is a whole other story.
Good luck
