Thanks for the key
@xaldub, it worked there, it just unlocks the back of an armoured car, as discussed it had only 1 lootable gun crate inside and it had an Il Torro shotgun and gun barrel mod. It was the last quest in the chain as well, so quest all done now.
PSA - For anyone that has an armored car key drop for Blue Gate, it's not a "normal" key that gets you into a high security loot room. It's a bugged quest item that is only supposed to spawn during a quest, but has been incorrectly flagged as a normal item which can randomly drop around the map but is
extremely rare. If you find one it's good for essentially donating to anyone who runs into the bug with the quest where they loot the key and die before using it. If you don't safe pocket the key immediately and lose it on death it's lost forever. The quest will not respawn this key if you go into the map again. For anyone who hasn't done this quest just make sure to keep the key in a safe pocket at all times, make sure you don't do this quest on a free loadout as it lacks a safe pocket. If you do happen to be lucky an have an armored truck key then save it for any friends who might need it if they already have the bug. Make sure you have safe pockets equipped when you trade it in a round.
I owe Xaldub a beer, and a shotgun!
I also solo'd the queens harvester just now and got the legendary blueprints for the Jupiter and the other one. That was intense. They seriously need to fix the bugs in there as well, that's unacceptable for something already quite hard.