Muscle droids were used by the Fromm Gang during the early years of the New Order. The Fromm Gang had long relied on Annoo-dat Blue goons to impose their will on others. Tig Fromm, attempting to leave behind the old-world methods of his father, became convinced that using droids presented the future of the Fromm Gang and began to use muscle droids to intimidate those who got in his way. The droids did have a major design flaw–their shape made them unable to get back up if knocked onto their backs.
When the speeder racers, Thall Joben and Jord Dusat accidentally discovered Tig's secret base while racing in the Vaj Desert, the gangster dispatched muscle droids to their speeder shop to abduct them. Thall had already left but the droids succeeded in capturing Jord. Upon returning to the shop, Thall was told by Kea Moll what had happened to Jord. They soon came under attack from more muscle droids who had sabotaged Thall's speeder to prevent his escape. Acting quickly, Kea and R2-D2 activated the White Witch, allowing the group to escape and knocking the droids down in the process.
After the defeat of the Fromm Gang, one of these droids was captured by the Great Heep and forced into service mining fuel ore for the Galactic Empire.