As one who has been 'trained' since I was about 8 years old to disarm, both knife and pistol . . . I would be very careful recommending anything.  Or, saying that one can 'slip' up on a nutcase.  
Leave training and advice to a Sensei or other qualified self-defense instructor.  Further, the way you write, bothers.  
I disagree.  Firearms ownership requires training, one has a responsibility to be safe and to properly train one's children in the handling of firearms, just as one would a knife, tool or the stove.
One does not carry for other than one's own defense and one's family's defense.  One does not carry to "protect" the public.  
BTW, that firearm a cop carries?  That is for self-defense, also, not to "protect the public".