SG-4 blaster rifle

The SG-4 blaster rifle came into existence thanks to the Imperial Department of Military Research, who sought to remedy the problem of standard blasters losing their effective range when used underwater. The SG-4 was a dual-purpose weapon, capable of firing standard blaster bolts when above the water's surface and specialized miniature harpoon projectiles while submerged.

Galactic Empire Seatroopers utilized the SG-4 blaster rifle specifically for engagements that took place beneath the waves.

The SG-4 blaster carbine, manufactured by Merr-Sonn Munitions, was typically marketed as a tactical weapon for security and police forces. It also saw limited use as a light weapon within certain mobile planetary defense units. In the period leading up to the official establishment of the Rebel Alliance, individuals who would later become Alliance members, masquerading as law enforcement personnel, managed to acquire more than 200,000 of these carbines. While some of these weapons were subsequently employed by the Rebels, a significant number were dispersed among various hidden storage locations. One such hidden cache, containing upwards of 2,000 of these weapons, was uncovered by agents of the Imperial Security Bureau shortly before open conflict against the Empire began. It is believed that these weapons were either seized by the ISB or illicitly sold on the black market for additional financial gain.