Board Thread:Questions and Answers/@comment-29321837-20160727144607/@comment-26523740-20170117065853

Juanito316 wrote: Ema kinda implied that LB needs to be in the sub only for Snipers... This is because although Snipers and Gunners use firearms to fight, Sniper's firearm (Eaglet,Ibis and Lightning) is a trigger whereas Gunner's firearm is (essentially) not. Which is why Chika can't equip LB in the same side as her firearm (Lightning) while Miwa can.

It is also important to note that LB (and Spider) is a bullet trigger. It was only categorized as optional due to it being non-destructive, unlike the other bullet triggers.