Since completing the "Show no mercy" Brotherhood Of Steel quest, every time I get into a Vertibird and then get out again I hold onto the minigun, which has infinite ammo, does not show up on the inventory screen, and every time I try to switch weapons it just says "This item cannot be unequipped". I sided with the BoS for the final part of the game, and since jumping onto Mass Fusion I haven't been able to unequip it (luckily I saved before). Also the only reason I chose the BoS was because the Institute side of it was glitched too :/