12 Gauge Incendiary Shells were added to RUST in Devblog 198, and it is an ammo type that fires sparking motes that turn into patches of flame when they contact the ground, surfaces, or players.
The ideal use for 12 Gauge incendiary shells is to deny enemy players’ movements by creating fire patches.
You can use the fire patches to block flanking directions or deny access to a hallway inside bases.
The fire patches made by the 12 Gauge Incendiary Shell have the added benefit of slowing the movement of players.
However, it is essential to note that fire patches do not affect NPC scientists or animals in the same way.