IMO 300BBC is cool but it was one of the first cartridges to do the thing it does (Heavy bullet sub sonic) in an AR package and because of that it's not as good at that as other more contemporary cartridges like 338arc and 8.6blackout.
not saying you are retarded but I think having both 300bbc and 556in the same setting is just asking for problems, not saying you are retarded but I've seen not retarded people blow up their guns.
Also See the SOLGW owner posting recently with his "warrarnty claims" of *totally not 300bbc in a 556* in a tweet bellow this methjob