"Striderteen, hitting moving headsized objects at 15 yards are not as easy as it may seem. If you've never been there, you never know what you will acually do.
Army and tactical training manuals are meant as supplemental sources of information, don't think that you'll learn everything from out of a book."
True. But they're a good place to start. Also, I don't think most stairways are 45 feet long. A quick aimed kill technique (line up iron sights, but don't worry about establishing sight picture) is good for up to about 12 meters.