I was interested in getting an semi-auto rifle, probably AR platform. I know Robinson arms makes their XCR in 5.56/6.8spc/6.5g, but I was wondering who else makes one. I think its just a matter of a barrel and bolt change, but who else makes them. This can also include bolt guns (I think desert tactical or something like that makes a bolt system/multiple barrel). Also, if you have FIRST HAND experience, please edumacate us...Thanks