It's been said here that Calfee(no opinion) uses a hardened steel hob, of some sort, to polish the throat. That's not what gave me this idea, but if true, would seem to give the concept some credence. I understand the lapping finish would be across the bullet path, but would it not be better than what the reamer leaves, considerably? You could always do as Jerry mentioned after this process, but just enough to change direction of the final finish. My thinking is actually, that it would leave a very smooth and more uniform throat, if done properly. Keep in mind, very light pressure and precisely following the exact leade angle. ...polishing if you will. Thanks