.70 cal is only .010" off being a 13 bore, while being .07" larger than a 14 bore. Of course, a brass case in a 'tight' 13 (.710") bore rifle, that is chambered for the 16 bore paper, fits a 16 bore brass case perfectly. 16 bore brass will hold a .700" ball or bullet quite handily.

My husky side by side with the straight rifled right hand barrel, has both chambers factory reamed for the 16 bore thick paper case as they are identical however the left smooth and choked barrel is meant for a shot load in a paper hull and the right barrel is meant for a black powder load with ball in a 16 bore, brass case. Perhaps similar circumstances is the reason why the .700"/16bore designation on this thread - ay, Lancaster?