Just this evening, while doing the daily heroic missions, as well as some of the bounties, I had a problem with ammo drops (ie: NO ammo was dropping whatsoever). My ammo would only get refilled by my using an ammo pack, or automatically when I was completely out. This was happening on 2 different characters, but seemed to resolve itself when I quit the game and relogged. Just want to pass it along to bungie and see if others are experiencing this as well.