Most machine shops, whether they have done any bowl work, rarely check for flashings that might and or will occur when the seats are pressed in. This is the same grade as a factory spec. Checking, rechecking, checking, rechecking, etc. are all time.Time costs money and most shops don't have the time to do 'IT' right. When you go to a machine shop, you must tell them exactly what you want and you must be able to see, in this case, the bare head before it is assembled.