Really emphasize the pinch at the top. I personaly like to do my DB shrugs the same way I would do something like crazy 8's. 20 rep full shrug and PINCH GODDAMIT at the top, then 20 totaly relax shoulders and go half way up, then 20 from the half way up, so 60 a set.. Don't do any of that bullshit were you see people rolling their shoulders backwards and forward unless you don't like your rotator cuffs. My traps aren't huge, but my genetics gave me pretty big ones for my size. If I were to ratio it out, or compare it to other muslces on my body my traps are abnormaly large. Also, how much weight are you using when you do BB front shrugs? To give you some perspective I weigh in the 165-170 range and when I do BB front shrugs I use 275.