Is one surface,of a dovetail rear sight set a 90 degrees to the bore of a 22lr caliber firearm barrel?

are you asking if the dovetail,open site is or are you removing said to place a scope mount,if so the grooves in the scope rail are at 33/3 degrees from center of bore,,if your installing a peep sight which i think your doing the rear sight is 90 ,,,also what type gun would help us in your answer ok