Thinking about peep sights? Want to know what height the front sight will need to be?
First find out what the height of the rear sight is at the midpoint adjustment in relation to the base of the sight. Most mfg's can give you this.
Brownells has a sight height calculator.
Need a set of calipers, a tape measure isn't accurate enough when you're talking changes that may be less than 5/100 of an inch.