The bug is still working...kill an clefthoove near the ramp of Auch around 44 72 and then use the drum. When the big worm comes, kite him towards the ramp and run down the ramp. Hide round the corner where u can still see him and he cant get u with posion spit. Shoot or throw at him couple of times and he will die after about 45 secs and u can loot it.

Hope this helps:)