The world of guns is changing fast... jobs that used to belong to military forces, like shooting bad guys, is being outsourced to drones.  And not only drones, but autonomous aircraft that have computer  brains that can make the decision to shoot if the right bad guy is in his way.

Reaper Hunter/Killer

This is starting to happen in your  back yard.  There are a million sentry gun projects in the works right now, not just military phalanx projects, but homebrew things made in a garage, and using cheap Arduino microprocessors and (for the moment) airsoft guns or rubber band gatling guns.  The computer controlled guns can be programmed  to aim and shoot manually or to make their own decisions and shoot when and where the programmer wants it to.

Airsoft gun and Arduino control

Of course, with the economic meltdown of the rich countries it's possible they are being developed at just the right time, and would make a dandy home defense weapon, but it would be hard to distinguish you going to the bathroom from a home invader.  Arduino's are pretty powerful, but I doubt they can tell friend from foe yet.  However, humans being the way they are, and inveterate tinkerers, they'll figure it out.

Rubber band Gatling with Arduino smarts