Sons of Horid prequets

Hello, i've been trying to grind the following item http://www.wowhead.com/item=41556/slag-covered-metal for around a day now and i'm wondering what the droprate is, i've talked to some and they say they got it on their 2 or 3 kill while doing the http://www.wowhead.com/quest=12915/mending-fences quest that you get from Thorim.

Anyone else experianced this?

Indeed the drop rate must be very low. I've killed about 40 mobs and they didn't drop the quest item. Maybe there is a new prerequisite for them to drop it that we don't know about.