Reader Anonymous writes "Tam, not meaning to beat a dead horse, but would you be willing to rehash the 6.5 vs 6.8 argument?"
First, it's hard to imagine a horse any deader. That particuly equine isn't just "dead", it is bloating in the sun, all four legs sticking stiffly upright. To boil it down to its essence, 6.5 Grendel is a target round that isn't taking the target-shooting community by storm, while 6.8 SPC is a combat round that isn't being widely adopted by the military. Both will kill something deader than Elvis. 6.5 might be more accurate at a bazillion meters, if that sort of thing's important to you.
Of the two, 6.5 seems more likely to get Betamaxed, though through no particular fault of its own. 6.8 SPC has been embraced by the two 800-lb gorillas of the AR industry, DPMS and Bushmaster, while the Grendel is still mostly the sole province of specialty shops like Alexander Arms and Les Baer (Saber Defense makes them as well, but for such a large manufacturer, they sure have a low profile in the retail world. I couldn't tell you where to lay your hands on a Saber AR right now if my life depended on it, and I do this for a living.) Remington and Hornady load 6.8, while for 6.5 you need to count on imported Wolf or boutique Black Hills. On the other hand, 6.5 has a rabid band of adherents with a pack attack rep on the web second only to f u r r i e s. (I'm sure they'll be along to correct any slander in this post.) In other words, 6.5 is already shaping up to play Mac to the SPC's IBM.
This kind of caliber stuff is enough to make my eyes glaze over. Seven years ago I could get in passionate spittle-on-the-screen flamewars over whether or not 10mm did or did not totally pwn .45 Super, j00 n00b. Now I have a difficult time seeing how someone can get worked up over it at all. The difference in actual performance between, say 6.5 and 6.8, or 9mm and .40, or .30-'06 and .308 is so miniscule that to argue about it is to talk just to hear your head roar.