I don't think anyone answered this question. Biggest pro in favor of the 6.8 is bolt life. Research AR15 performance and look at the 6.8 forum. eye opening and interesting. I have one of their 3r barrels in 6.8.I had a 6.5 Grendel at one time. Just trying to figure out if I want to go down the same route. Give me the pro and cons of the 6.8.