As usual,, I agree with Flatgate. The Sweeney book is an ok read,, but there are several things that are a bit wrong. But,, so far,, NO book I've read on Rugers is 100% correct. But the ones mentioned above come mighty close,,! However,, the latest Dougan book DOES have an addendum to correct the mistakes all the proofreaders missed. That's the nature of the beast of publishing. You try & try to get all the facts correct,, yet,, it's easy to miss something,, or when it goes to the printer a mistake is made in layout etc.