Shot counter

[Hoosier]

http://www.engadget.com/2011/02/01/m...omatic-weapon/

Built by a non-gunner for his uncle, counts your shots to tell you how many rounds you have left in the mag, video-game style.

I don't think the electronics to build this are that complex, the accelerometer chip inside is also used for autopilot on R/C aircraft.

H.