Heroes of Ruin

there is a legendary set of gun slinger guns that ressemble machine guns, they have a yellow frame with a silvery MG shaped barrel and they're obtained through certain boss win, strange thing is i went through gunslinger and finished it but never recieved the guns through treasure box, so if anyone wouldnt either trading me them for one of level30 guns or tell me what boss is needed to be beaten in order to obtain them, i would be greatly appreciative,

Thx
P.S this is my FC:0001-3948-5648,just in case you wish to add me
Lv30gunslinger,Lv30Vindicator(Skyknight)

You're thinking of the 'Atomic Arms', right? Pretty sure you get them not from a boss fight, but just from a regular fight. I have a feeling it's the one where you toss Mia Moursey's ashes into the Well of Souls and report back to her sister. Have a feeling that's how I got Atomic Arms, hope this helps