[owenslee]

I know this may be opening a barrel, but do you recommend an upper for my gun to go to the 6.8. I was looking at the RRA upper but they are only 16" and I think I would like 18 or 20.

If your going to own just one 6.8 SPC upper, I would buy an 18" bare upper with Free floating hand guards from Tim at Ko-Tronics. It's accuracy is as good as anything out there plus it has a chrome lined bore. In addition Tims customer service is top notch.
You don't need a compete upper with bolt carrier and charge handle. Just a bare upper with a 6.8 bolt added and the muzzle device of your choice. Then use the bolt carrier and charge handle you already have.

Kerry