Speedmaster intake porting. Hopefully I can make something out of this

If you're really good, you can buy a 6" shank burr and carefully heat it a dull red about 2" from the end and put a 45 degree bend in it. That let's you reach around a lot of tight corners.
Maybe I’m missing something, but doesn’t that cause the burr to “slap” around? Seems like that would be impossible to control?