I have used the Miles Gilbert inletting black and it works good. A good characteristic of it is that it stays on the metal for a while without having to re-coat it after every try at fitting. You can fit and remove it several times before having to put more of the black on.
In regards to using lipstick. It goes on easier than typical inletting black and cleans up a bit better, but it is a bit too pastey and thick. It also does not stay on the metal for long after trying to fit. I have found that the best place for lipstick is on barrels for fitting forends and barrel channels.
