AR Conversion?

[Hillbilly270]

so i have a rra ar15 in .223 and I also have a cz 527 in 204.  What would it take to make my AR shoot .204 besides purchasing an upper?  would i have to get new clips for it?  bolt carrier?  etc...  anyone ever do this?  I think it would be sweet to shoot a semi auto 204.  more expensive but 
thanks

[Big10gauge]

New barrel and bolt face, Look at model 1 sales, It's almost as cheap just to buy the upper

http://www.model1sales.com/

[demontang]

Just a new upper. You could swap back and forth with the 223 quick and easy