Period-44 glider gun is a glider gun with a true period of 44. The first one was found by Dave Buckingham on April 2, 1992. It used two interacting copies of an oscillator which he also found. In October 1996 he found a variant of the gun which only used one copy of the oscillator. Paul Callahan improved it in 1997, resulting in the gun shown in the infobox. It can be converted to a double-barrelled form by making the top half of the gun a mirror-image or rotated copy of the bottom half.