Vault of Glass with six people is a much better way to farm keys. 3 people at Ember Caves and 3 at the Citadel. Usually Ember Caves will happen first and if your group is fast enough they can catch the Citadel right after. The only downside is that it's a bit more crowded and you can bump into one another. Also, make sure your consumables are full and have a key with you if possible so they can stack. That way you won't receive special ammo synths. If you don't have a key I still suggest keeping your consumables full until you get one, it will be sent to the postmaster but will not pop on the screen. It will say you found a key on the lower left side of your screen so keep an eye out for it. You're welcome OP, now make a new video.