Sentence:  Bill Ruger 's long-awaited Deerstalker ( under $ 110 ) is a new rifle action in a caliber that <WSD>upsets</WSD> all the modern theory of high-velocity fans ; it 's a short , light , quick-handling , fast-firing little timber gun designed to push a heavy slug at modest velocity but with lots of killing power and ample range for our most popular big game - whitetail . 
Meaning of the word marked with <WSD> tags:  disturb the balance or stability of