I have an AR-15 Lower Reciever, parts kit, buffer tube, etc. Now I'm trying to decide on which caliber to go with. I've read good things about both rounds (6.5 Grendel, or 6.8 spc). I was initially going with the Grendel, but am a little uncertain now. I plan on using it to shoot medium size game (Deer, Hogs, Catalina, etc.). I'm planning going Johnny Cash style on this, "One piece at a time!" So it will be over the course of the year before I'm finished with it. So here's the question. If you could only build one AR-15 and you had to choose between the 6.5 Grendel or the 6.8 SPC. Which would you choose, and why?