How do you think the Bereans were expected to do this before the Canon of Scripture was completed and even before the Letters of Paul were completely written? Can you think of a single New Testament verse in which a reference to Scripture was something other than a reference to the Old Testament?
That really is laugh out loud funny. Throw out books that the Bereans had as a part of their Scriptures because Luther didn't like those books, ignore the fact that Christ never said a single thing against the existing selection of books that were included in Scriptures at the time, nor did any Apostle, and then laud the Bereans. I don't recall anything about Bereans first selecting what subset they would accept and then searching the Scriptures.