Canonical Fantasy
XBC-BW-79G Mobile Suit Light Beam Cannon 'Light-Cannon'
A lightweight version of the Guncannon II's beam cannon, designed to supplement the GM's firepower. To test its impact on mobility, it was given to several aces specializing in high-mobility combat, including a woman nicknamed "The Witch," and deployed in actual combat.
(Simply the light cannon's beam cannon was mounted on a GM)

A fantasy about a light cannon in the official history. | kumadanko_001's Gunpla works