you're welcome. i don't know about the AP US book,
but the Kaplan SAT prep book is easier than the real SAT test.
so i would use another book besides the one from Kaplan.
The book my APUSH teacher recommended was REA.
here's the link if you want to look at it
Amazon.com: AP United States History (REA) - The Best Test Prep for the AP Exam: 7th Edition (Test Preps): J. A. McDuffie, G. W. Piggrem, Steven E. Woodworth, Gregory Feldmeth: Books
as fhg said, Barron's is way harder than the real test,
so I'd recommend you to go with some other brand.