There was a topic similar to this on the old forums a while back,roughly 6 months ago
. I believe it was Eze from dgg guild who complained of the same thing happening to him.He couldn't get the weapons to drop that he needed either and he did quite a few QH's.Beleg who at the time was with ttn replied and said he was having the same trouble also and he took out well over 100 QH's looking for a weapon for a fellow guild member or to help someone else out.
Unfortunately with all the added extra wisdom and agility junk along with life and power we had already....the drops are few and far between for guardian,enchanted and scoped weapons now.the only thing you can do is keep trying and trying or ask around and see if anyone else has a spare scoped gun they don't need.