Make sure you're still doing the exotic gorgon chest in the VoG and Atheon! That's how I got mine a few weeks ago and one dropped just yesterday for a fireteam member at Atheon. Also, for a friend last week at the exotic chest. AND as of next week, the VoG exotics will be lvl 32 so that there will be no necessity for upgrading! It is just luck. Just play the game and stop looking ;) let it find you, haha