At the end of the Tidal Basin mission you can destroy the turrets, pick up the loot, let the team wipe, and repeat the process. The turrets keep dropping loot (most importantly exotics).
Hello everyone, thank you for getting in touch with us about this exploit, we will pass this information to the dev team to look into.
As for the Stage Left weapon, this is something the Dev team are aware of and I believe a fix is coming soon, if not, already been applied in-game, thank you.