I was just wondering the same thing and came across this post in a search. It seems the Cylinder & Slide part sits at least as high in the frame as the stock S&W adjustable sight. If you still need an answer to this question, Dawson Precision has a link in its Front Sight section that gives a formula for determining the proper height of a front sight, in relation to where your bullets are currently hitting on the target.

Dave Sinko