On December 19, the devs confirmed they'd nerfed the shotgun again by disabling the powerful Dual Trigger attachment. We've deployed an update to disable the use of the Maelstrom Dual Trigger Attachment on the Lockwood 300 Shotgun in public Playlists.
If you bought it for just the shotgun because the Lockwood was busted on Season 6 Patch, you bought it for the wrong reason. Don't feel bad at all for those people.