If you had a 6mm ARC in an AR, it would be a fun wildcat swap to do a 8.6 ARC for a shorter range whomp or subsonic stomp. 160 grain bullet would be a great choice for supersonic and up to 300 grain high BC bullets for subsonic.

Nope not for me a 6,5 Grendel would be nice for 160gr bullets, my 300blk can do the subsonic stuff well. An AR would throw away all the brass you have made for 8,6arc.