The BARM-ST12 scattergun was a pump-action weapon classified as a scatter blaster.
Lang, a mercenary, possessed a BARM-ST12 scattergun. In his confrontation with Ahsoka Tano, he discharged a volley of energy projectiles towards the Jedi, but failed to hit her. Before he could ready another shot, the Jedi had already become aware of him.
Although blaster shotguns have appeared in Star Wars Legends for a considerable time, the scatterblaster made its debut into the broader canon visually in Chapter 13: The Jedi of The Mandalorian. In a short sequence, the character Lang uses his BARM-ST12 scattergun against Ahsoka Tano while she is positioned on a rooftop, demonstrating that the weapon discharges 4-5 blaster bolts concurrently. In that same scene, Lang prepares his weapon using pump-action.