6x45, 6x43, 6x47, 243/222, 6mm/223. Rifle, Barrel, dies etc WANTED

Description:

I am looking for any items relative to the adaption of 6mm (or other) projectiles to the .222 or 223 family of cases.
I am particularly interested in building a short range rifle in 6mm or 25 cal based upon the .221 or .222 case and would be very interested to hear of anyone's experience with these.
Yes also interested in .221/30 and .30 B.O.
As a base for the project I am also looking for a mini length actioned rifle preferably with drop out magazine I.E. Brno, Sako, Tikka. As this will be a rebarreling project the condition of the current barrel and or stock is not important