I have a Bushmaster flat-top version in 223 with a 20" heavy barrel.  I would like to buy a different upper receiver to hunt deer with.  I have read a few articles about the 6.5 Grendel and the 6.8 Remington SPC.  The 6.8 SPC has impressed me, at least as far as a magazine article can go. 
Does anyone have experience with this 6.8 SPC or the 6.5 Grendel??  I have the $$ burning a hole in my pocket, need to buy an upper before I spend it on something ridiculous like bills.   :grin: 
Thanks, Mainehunt