u/CISDidNothingWrong

One of the brotherhood guards outside the washington monument had it equipped, so I shot it out of his hands before holstering my rifle to deaggro him. I don't have enough ammunition for it right now but turns out that I'm doing a heavy weapons build, so this and the missile launcher I found will come in handy when I transition from small to big guns.

Edit: I came back a few hours later and he respawned with another one, so I figure I can just farm infinite Gatling lasers off of this guy ahahahahaha