Normally, It won't work with legendary but with the update of agent modifier, it's now possible to use it in legendary mode with 500% headshot damage. (You get 350% of headshot damage if you have all three of 10% headshot mod. 150% plus of headshot damage if you equip "Tapper" passive modifier. And boost sniper damage with "cull the weak" passive modifier.) Ps: Equip "White death" to boost headshot damage.
Build?
Normally, It won't work with legendary but with the update of agent modifier, it's now possible to use it in legendary mode with 500% headshot damage. (You get 350% of headshot damage if you have all three of 10% headshot mod. 150% plus of headshot damage if you equip "Tapper" passive modifier. And boost sniper damage with "cull the weak" passive modifier.)
Ps: Equip "White death" to boost headshot damage.