Ben,

In 1993 (I think) Rigby made a 10 bore rifle with barrels from Joseph Hambrusch and the rifle was used to hunt Cape Buffalo in Tanzania. Gun Digest article carried a detailed article on the gun, on the loads developed for it and of the hunt. I have a copy but it is with my personal library in India. If someone has a copy here, they may scan and e-mail it to those who may be interested. From what I recall, the rifle performed admirably on the hunt with the new, Nitro for BP type loads developed for it by Rigby at the time. Subsequently, Paul Roberts sold Rigby to the present owners and they decided not to make these rifles anymore, I guess. You would enjoy reading the article if you find it, espoecially because you're interested in the subject.

Cheers!