Abstract: A conveying and separation assembly for the impact material of a ballistic projectile arrester for indoor firing grounds, of the type that comprises a heap of granulated material as the impact material, and a pneumatic conveyor for sending the granulated material once it has been separated from the exploded projectiles up to the top of said heap. The assembly comprises a variable-diameter worm screw or helical screw, that rotates about a horizontal axis and is arranged within a half cylinder which is open at its upper portion, the worm screw lying in a direction substantially parallel to that from which the projectiles come; a motor for the worm screw; and gravity separation of the exploded projectiles from the granulated material; the half cylinder being connected, at its rear terminal part, with the worm screw or pneumatic conveyor which are employed for sending the material to the top of the heap.