The bullets that this thread is based on are jacketed lead.
That is not stated anywhere, least of all by the original post. Given that the thread will be read by users of copper monos as well, it must be stressed that the Miller Formula does not do well with copper mono bullets. It also gives a margin of error with certain types of jacketed lead bullets but it is easy to use. That is the attraction and the temptation - ease of use.
As with most things, easy is not always right and it needs pointing out.
A good example is the easy way to calculate SD: Bullet diameter squared, divided by bullet weight is easy, but it is not right, is it?