If someone is attempting to disarm you--what are the consequences if he succeeds? In my opinion, you are justified in shooting someone attempting to get your gun in most instances. The cops do it all the time. Now, if you are 6'4" and 260 pounds and your assailant is 14 years old and 105 pounds, then please disregard the second sentence.
Int'l Assoc. of Law Enforcement Firearms Instructors