Bill, thanks for the pix, it helps.....

So, if the .204R is a 20 cal .222 Mag 'Improved', I'm thinking that what I want is simply a .222 Mag AI. This way, I could use the .223 Rem bbls. All I might need, is the .222 Mag brass. I haven't checked, but I'll bet RCBS makes dies.
I have a universal .22 CF neck die.

What do you think???

ron