Th 243 wssm beats the 6mm Rem by a whole 10fps with a 100gr. bullet. Its not worth the extra expense, and the problems of finding brass and ammo. Like RR stated, AI it and then you will have a hot 243 caliber round, if that is what you are after. Personally, I beleive the plain 6mm is fine just the way it is but everyone is different and has different ideas and opinions.