Taylor might have that info in his stuff, somewhere. He's refurbished a few Bess' for folks. Seem to me they were all around .80 cal. Along with a quite short length of pull and the the lack of drop in the rather sharp comb, the Bess stocks I've shouldered, showed a rather squarish comb edge - all contributing to bruised cheeks if not shot with a 'high' face. This, of course, lends itself to very high shots.