I think what they mean when they say 40 brass necked down, is that it starts life as the same shape but is not trimmed as much to allow for the length the necking takes back.
Good point. I've just heard some people talking about .40 S&W necked down and since I reload that catches my ear because it is potentially very dangerous if someone tried it.
I toured an ammo factory museum as part of a ME class at GMI. Really neat how they are made.
I've always wanted to do that. I hear it's a really interesting process. Is the brass mostly extruded or is there some other way of pressing it into shape?