You don't need any punches or break free. Kimber puts their sights on very tightly in the dovetails. Break free isn't going to help. Just hit the rear sight with a leather mallet or a nylon hammer after you remove the screw. It's not going to hurt anything and the leather or nylon will not damage the finish. Brass punches are just going to deform and squish and leave brass marks all over your gun and sight that you will have to remove.

Do not do this with the front sight. You will break off the blade.