What is the 480th Year all about?

            1st Kings 6:1 says:

            KJV 1 Kings 6:1 And it came to pass in the four hundred and eightieth year after the children of Israel were come out of the land of Egypt, in the fourth year of Solomon's reign over Israel, in the month Zif, which is the second month, that he began to build the house of the LORD.

            The text is mistranslated.   It should read:

              1 Kings 6:1 And it came to pass in the four hundred and eightieth year for the Exodus of the sons of Israel from Egypt, in the fourth year of Solomon's reign over Israel, in the month Zif, which is the second month, that he began to build the house of the LORD.

            The words "for the Exodus" refer to the annual Passover celebration of the Exodus.  What is being enumerated in the 480th year, is the 480th annual Exodus celebration.   The 480th year counts all the times that Israel celebrated the Exodus, leaving out all those times of rebellion or oppression by enemies when they were unable or unwilling to celebrate it.   This is especially more true, when we learn that for the last two oppressions by the Philistines that these people were vassals of Egypt, and so not outside the jurisdiction of Egypt.   When oppressed by the Philistines, Israel could not claim independence from Egypt.

             This is more completely explained in the book.  See here.