I recently obtained the Salvation's Grip exotic grenade launcher with my clanmate (he was a step ahead of me and I joined him in the mission, and ended up getting the grenade launcher with him). I did finish the quest and the mission for the grenade launcher (Stealing Stasis) myself as well on that character, and while I can dismantle it, if I do, The Drifter just gives me another one when I try to get bounties from him for gambit. I've tried talking to him after he gives it to me and it just brings up his 'shop' menu for bounties and won't let me turn it in.