You hear 2 bolting/rechambering sounds simultaneously, both the unique sci-fi one (that is part of the fire sound afaik) as well as a regular CHACHUNK sound that is NOT CORRECT for the weapon nor animation! (This happened a long time after the gun got released, some Jr dev thought they were fixing a bug by giving this weapon the CHACHUNK sound most likely) This is an easy fix that most likely involves setting the rechambering sound of this weapon to null... as it was originally.