Disintegrator gun

The disintegrator gun was a handheld weapon from an alternate Earth in the 22nd century. It employed an ultrasonic beam which effectively "disintegrated" the target. It was the weapon of choice of the human resistance opposing the Daleks and the Ogrons of that time in various forms. They were apparently made of steel composites. (TV: Day of the Daleks)

Another disintegrator gun was stolen by the K1 robot on orders from the Scientific Reform Society and used to break into Joseph Chambers' safe, which contained the destructor codes for the world's nuclear missiles. The Brigadier retrieved it and fired it upon the robot. Its living-metal status allowed it to absorb the power and so it only grew. (TV: Robot)