I just unlocked gold Assault Shield this morning. Go play Hardcore, and use tacticals (concussions, shock charges) generously. It's a little painful, but not nearly as bad as the Bloodthirsty for the crossbow!
Gold shield was surprisingly easy, other than getting kills with no perks or tacticals. The crossbow bloodthirsty is just cruel. I'm pretty good wth the crossbow, but the game doesn't always cooperate. I already have the combat knife, so I don't think Ballistic will be too bad, only about halfway there on kills so far, though.
all i have to do now is the shield and i am glad i did the cross bow 1st cause that bloodthirsty for it took me a month to get then i did the combat kinife then i did the balistic kinfe but if i knew i had to do the shield too i would have saved the balistic knifes for last
Only thing about the shielld is when they say "no weapons" they mean nothing at all- no secondary, no lethals and no tacticals. Getting kills with no tacticals, and stacking that with no perks, was slow going, but it isn't that many kills. Only 30, I think. I was going to do one then the other, but I stuck it out.