The Avengers: Endgame box office is poised to be absolutely unprecedented. Fresh off a record-breaking $60 million from Thursday night preview showings, Disney is now cautiously projecting an opening day gross of $140+ million and an opening weekend gross in the range of $300 million, both of which are insane. Avengers: Infinity War currently holds the title for the biggest opening weekend of all time at $257.7 million, so if Endgame cracks $300 million, that’s not just breaking the record, that’s shattering it. As for the opening day total, Star Wars: The Force Awakens holds the …