Hey Guys i just have finish all 5 Spartan Ops Missions on Legendary ( 4 Co-op )
and i dont got the archivement 
a bug ?
anyyone with tha same problem ?
and i dont ogt the knight avatar helmet for the assassinate archivement
can anyone help ?
haha and i dont got my mk 6 helmet D:
i have done my campagne solo on legendary