Boba Fett firing his Sacros K-11 blaster.
Boba Fett wielded one such weapon on Panna Prime. He attempted to fire on a pursuing Stormtrooper speeder as part of a ruse to fool Chewbacca into accepting him as an ally. Chewbacca became irritated at his apparent poor gun skills and seized the blaster himself, shooting the speeder into pieces.
An animated version of the Sacros K-11, as shown on the Boba Fett Character Key from Acme Archives.
This weapon was first named on the "Holiday Special Boba Fett Character Key" from Acme Archives. The Boba Fett "Black Series" SDCC limited edition action figure had a breakdown description key of Fett's weapons, listing his Empire Strikes Back blaster as a "Sacros K-11 Disintegrator Pistol."