Actually, pisgah, I was addressing Marshal Kane, since you said nothing about bullet shape in relation to leading.
I agree that any one factor causing leading can usually be worked around by tweaking the others. If you start to get leading when you raise the velocity, try tweaking the alloy, size, powder, etc. The same goes for bullet shape.
Say you have a non-leading load for a RN bullet. Say you try that same load, but using a SWC, and now you get leading at the forcing cone. Try using a softer alloy or sizing larger (if the throats allow). Just an example, but all I'm saying is that it would be false to say that the shape of the bullet never has anything to do with leading. Bevel based bullets, for example, are notorious for leading, and I've never been able to get a powder/alloy/size combination to eliminate it for my bevel based .38s.