Maxson's weapon after completing the Brotherhood of Steel (Fallout 4)

Gentlemen, the following question has matured:
After the destruction of the institute and indeed the completion of all the main tasks for the Brotherhood, Elder Maxson gives me only a jetpack for Power Armor! But I read in many guides that it should also give out cool fluff (Gatling laser, if I'm not mistaken). So how do you get this weapon? Are there any conditions for obtaining it?
I ask you to answer this question, because I really want this fluff)