They are right 305 X 10 DL is a mans exercise!
Here is a thread on the training I was talking about. It is a little different but laid out by one of the all time great grip strength guys David Horne.
It is on the gripboard and you have to register to view the forums. I don't post there but man there is a ton of information to read. It can get quite overwhelming actually.
What we think, or what we know, or what we believe, is in the end, of little consequence. The only thing of consequence is what we do. -John Ruskin