I think the Peterson B10 is a briar Calabash shape because of the way the brim arches up from the edge of the bowl. I have a modest version of it that I find excellent. The chamber is of good size, and the bowl and bent shank and stem fit nicely in hand. It's both compact and big enough, nicely balanced and visually pleasing. Mine has rough rustication which isn't everyone's taste, but it looks good to me and improves with age, and doesn't have to be treated with kid gloves.
While we're in the B series of Petersons, I also like the B11, which is a sitter volcano (or you might call it a brandy, since it has both shape attributes). It's another shape with a commodious chamber and a nice balanced shape. I have two B11's, one plain brown stain with a black stem, and another ebony with two thin bands, a dress pipe.