I know, yes, and I've read just about every article on 6mmbr. Tube length being the biggest factor here. I know it'll do it, that's why I wrote the original post the way I did.
P.S. The 284 Improved cited decreases body taper by .010", not to .010"; and the shoulder is left at 35deg. This is the 284 shehane, discribed on 6mmbr. There are countless "Improved" versions of every cartrige, so I'm sure there is one that does exactly what you're describing.
Oh, and I may start adding *grin* at the end of my setences, since no one on this site can pick up on sarcasm or joking in my posts.