Ok, I misunderstood.
St Augustine has a different take than Berry/Kramer, FYI.
You're right, he does. Fr. Kramer states in a note after his Bibliography that he avoided relying so much on the Fathers since they tend toward the spiritual interpretation more than the literal.
The commentaries and interpretations of the great Doctors of the fourth and later centuries and of the theologians of the Middle Ages have been skipped, because they gave the interpretation of the Apocalypse a purely “spiritual” direction, even before St. Augustine. Only modern scholars and theologians and scripturists have searched more deeply into the writings of ancient Fathers and into the prophetical books and fragments of prophecies of the Old Testament. They have come nearer to the true meaning of the prophetical visions and words of the Apocalypse than the doctors and theologians of the Middle Ages.
I understand why he would say this, because of the larger selection of resources available to contemporary exegetes compared to the past. As well as the potential for us being "closer" to the unveiling of these prophecies given all that has occurred between the age of the Fathers, the Middle Ages and today. For example, the opening of the seals, in both Berry and Kramer, looks at the various heresies of the Church over time; something unknown to some of earlier Fathers who were either actively fighting those heresies at the time, or, that they would come later. Specifically the "opening of the Abyss" being associated, I believe in Kramer, with the Protestant Revolt and all that came of that over the past 500 years.
This isn't me trying to dismiss the insights of the Fathers and Doctors, but, when it comes to the Apocalypse, it seems more prudent to take a more recent (but thoroughly orthodox) commentary given all that has occurred in Church history; especially in light of the Apocalypse being by-and-large a prophecy of the Church herself.