Aliant did come out with that 300-MP not too long ago. It is designed for magnum handgun loads. But it is not in any of the reloading manuals yet so we'll have to wait until the next editions to see it there.
I think he was referring to 300-MP when he said this, not 2400.
I am also waiting for more info for 300-MP, hard to believe what is claimed about it. Till then I will stick with 2400.