Rawhide and Triple Master working

How are you guys getting raw hide and hitting triple crits on your master working? I am having the WORST luck, zero triple crits and i've been master working a ton, until I ran out of rawhide that is. Now i can't get anywhere, what's the best way to farm, and how is your master working going? I'm paragon level 274 with zero tripple crits and only one build all season. UGH