This weapons video will show you the fastest, most positive way to disengage the Beretta 92FS slide-mounted safety. If you own a Beretta 92FS pistol, you may want to know how to correctly disengage the safety.
Center the handgun in the web of your hand, i.e. assume the correct grip. The thumb starts up high, bumps the safety forward with the first joint, and finishes in a down and forward motion.