As the title says, the perk Quickdraw, on Sniper Rifles is deactivating/disabling itself after an extended period of time "alive". It can be fixed by simply dying or switching to a different special weapon and back (changing perks doesn't work, I tried), until it disables itself again. It's not a problem in PvP since you can't stay alive long enough in to have this happen. In PvE however, it becomes quite an annoyance when you're someone like me who prioritizes staying alive above anything else.