From Destinypedia, the Destiny wiki
Forerunner is a high damage Kinetic-slot sidearm, unique in its use of Special ammo. This may remind Destiny 1 veterans of sidearms in that game, before they became standard primary ammo weapons with the release of Destiny 2. It also comes equipped with a short range scope for easier target acquisition. Firing at full auto, it can deal out heavy damage in short shrift, though it exhibits strong kick when fired fully auto. As a trait, tap firing the gun provides less recoil and improves accuracy on each shot.
Its catalyst trait provides the ability to exchange your grenade ability with a Fragmentation Grenade after a kill, at the cost of 6 ammo, which inherits any effect associated with grenades being thrown, damage being dealt with grenades or kills made with grenades.
Acquired by reaching Reputation Rank 16 with Xûr, the Catalyst adds the following perk:
The form of the weapon suggested an oversized sidearm—a secondary weapon for a giant's hands. The function presented more so as an anti-material rifle. "Looks to be 12.7mm... it's like they were making a hand cannon but didn't know it yet."
The weapon was laced with fractures from a life of fire and a sleep of ice, and perhaps other, more exotic stresses. Banshee wished he could've heard the relic's voice, but he knew from earlier examination that it had fired its last round. What a last round it must have been.
The Guardian who brought it to him might be willing to try a shot, untroubled by the risk of a rapid unplanned dismantle. But Banshee knew it wouldn't last through a single magazine.
It would be an homage, an offering to the creators of the original relic. A legacy.
With that satisfying thought in mind, the gunsmith went to work.
List of appearances