How rare is the gatling laser??

yeah I just realized im level 80, I have never even seen a gatling laser. I am at the point where im supposed to go find Virgil in the glowing sea. I have been on the prydwen. I have killed a ton of BOS patrols I see. yeah I havent even seen a gatling laser, and also I havent seen a legendary minigun except the ash maker. im trying to use big guns finally and all I have is the freezing flamer. I have been buying all 5mm and fusion cells for 40 levels and havent gotten a legendary of either yet!!