I want to build a 6.8 Ar type rifle. I was looking at the MUR upper with either the CASV or daniel defense rail. A Noveske or LWRC lower. But I don’t know if the MUR .223 will fit a 6.8 bolt and bolt carrier, I thought it would work but someone told me that it wouldn’t, that just a .223 lower will work? Any thoughts. And I don’t know what kind of bolt and bolt carrier to go with, I want to go with a chrome bolt and bolt carrier and the only barrel companies I’ve dealt with other than ar manufactures is Krieger. And I was totally pleased with my barrel for my Ar 10 (T). But I believe he doesn’t make a 6.8 barrel. Any suggestions or comments would be very appreciated.