Robert: Sweeney only discusses tumbling in the context of "tumbling occurs in certain mediums which leads to the bullet breaking apart at the cannelure", not as the main component of the damage the bullet does. In fact he goes so far as to list a few ranges at which a M193 spec bullet stops fragmenting at, and then simply tumbles- and goes further to say that past
that range, the bullet does neither.
Also... What else do writers have to go on, other than doing it themselves - which is difficult to do when putting together a comprehensive book such as this? Credit him with at least going to the right sources for his research.
I'll also give him credit for putting Ammo Oracle type conclusions in a mass market book instead of dredging up the stuff we're accustomed to seeing in books (either outright fallacies or simply ignoring it because it's an ugly subject).
Note, I've noticed many typos and an inaccuracy here or there, but nothing is perfect and frankly, I still think the book is a solid buy. Get it from the Amazon link so you don't have to pay full price like I did.