Both will do very well for game...the 6.5 Grendel will give you more distance if you want to shoot longer ranges.
I've owned the 6.8SPC and the bullet choices aren't great and BC isn't on the same level as the 6.5 Grendel.
You won't need a 20" + barrel on a 6.5 Grendel...it's overkill actually as you aren't getting such a benefit of added muzzle velocity going to a 26" barrel. You are just going to go with a heavy bench rifle.
Make sure if you get a grendel that you choose SAAMI chambers vs the "type 2" chambers.
I swear so many people on this forum have a tough time with reading comprehension as the 308 comment isn't even on an AR15 platform.
Last edited by aubie515; 09-05-2017 at 10:05 PM.