Ah. I see. I misread/misunderstood the original post.

I have no idea what size of bushing but among people that use those types of dies they tend to get a set of them instead of just one. I've personally never really used them myself so I don't know what size of bushing to use.

Like I said though, the Mighty Armory are expensive but I like them a lot. I will look around and see if I have another sizing die for 6 ARC. If I do it's all yours.