I don't know about the WWB connection, but I have heard similar theories about WWB/S&B. It's all good ammo.
There are several conversion factors for relating penetration in water, in various containers, to penetration in ballistic gelatin. “Friar Frog’s” page at
http://www.frfrogspad.com/miscelln.htm opines that “bullet penetration in water is 1.8 times that of ballistic gelatin and in milk cartons somewhere generally around 1.5” Frog is pretty close on most things, and I suspect he has this down pretty well too.
I personally think penetration is a little less when you use plastic jugs, and my mind is comfortable with this simple statement: “Handgun bullets at typical velocities will penetrate a little deeper in water-filled one-gallon beverage jugs, than they will in gelatin. Using three of them provides ample resistance to recover most expanding handgun rounds, and the walls of each jug provide an additional stress factor as the bullets expand.”
A similar test involving several better-known .45 ACP loads is located
here for a frame of reference.
I think the tested.357 JHP 'books' at 1400 fps, and it produced a shade over 1300 in the 6 1/2" Ruger. I didn't have a 7 1/2" or 8 3/8" sixgun handy but I think either would have gotten close to the published figure.
Glad y'all enjoyed this.