The H&H 10b Paradox was actually closer to a 9 bore.

Here's an excerpt from The Field, September 15, 1906 in which H&H answers a question concerning its philosophy in developing the heavy 10b Paradox:

This was re-printed in Baker & Lake, Paradox, The Story of Col. G.V. Fosbery, Holland & Holland, and the Paradox, Vol. 1, page 184.

I am sizing my bullets to .805", which is about a thousandth below actual bore diameter.

I will be quite interested to hear how your shooting goes with the Purdey. Do you know what bore dimensions they are using? What ammunition will they use for regulation? Will the case be brass or paper (plastic)? What will be the finished weight? Many questions!

Curl