Not sure if I can help but its a starting point I did some quick searches and found one wiki dated for ~2011 FBB=Farferons BraveFighters im sure thats not COD though.
Found COD clan of FBB on Xfire= Friends Before Betrayal 3 members listed.
Steam has a group that is COD listed as FBB=FunBallerBurg
Elite dot CODdotcom search clan returns FBB one member
not sure if this is what your talking about in "Gold tag" I dont do much in levels and achievements I just play the game and shoot ppl and haven't been in a clan for many years