Tim, If you are referring to the one that Chance_livewire has listed, he says it is a 6mmx284. I know this doesn't make a difference with your caution since they use the same case, but just wanted to clarify that it is the 6mm not 6.5mm.
I have looked at the ad more than a few times. It is not a cartridge I need. But that hasn't stopped me before (spoken in true Handiholic fashion). It is a good price for what you are getting, barrel, dies & brass. I had better stop before I go look at the ad again.