All of the Baron gear now only drops during a Tangled Shore flashpoint. When TS is the weekly flashpoint, your first completion of the daily Heroic Adventure gives you a guaranteed drop from killing the Baron, and repeat runs in the same day only have a chance at a drop. The next day, you can do the Heroic Adventure for another guaranteed drop on your first run. Be aware though, there are also a sidearm and a grenade launcher that are possible drops instead of one of the armor pieces.