Destabilizing Rounds is a trait in Destiny 2 that can appear on 98 weapons. An enhanced version exists on crafted and some newer weapons.
What Destabilizing Rounds does
Defeating a target creates a Void burst; hitting other targets with this burst makes them volatile and grants you Volatile Rounds for a short duration.
Enhanced version
Defeating a target creates a Void burst; hitting other targets with this burst makes them volatile and grants you Volatile Rounds for an improved duration.