Dani: taken from the link given in mess #199:
The pistol discharged shortly before noon Saturday aboard Flight 1536 from Denver to Charlotte, as the Airbus A319 was at about 8,000 feet and about 10 minutes from landing.
Servicing a gun in the cockpit 10minutes before landing?
There must be other, safer, and potentially more efficient ways to prevent someone to take over control of an aircraft. Might involve more cost and more inconveniences for all involved, though...
In this case, everyone on board (and potentially on the ground) was very lucky...