Let's try this again!
Question was, "Ballistics wise, how does the 6.8 SPC compare to the 7.62X39mm in an AR-15?"
Simple enough?
No 6.5 Grendel, no .300 Blackout, no .308W.
No comparison of the 6.5 Grendel to the 6.8, no comparison of the Grendel to the .308W.
T.