Remington wasn't the first one to this party. Olympic has had the big bolt on a standard AR for several years now going up to the Short Mag.

I've had a .473 bolt faced (same as 308 Win) 6BR for a couple of years now.
[Linked Image]

Here's a corrected link to the earlier referenced article in case anyone else had trouble. It was actually a pretty good review.
http://www.shootingtimes.com/longgun_reviews/ST_r15andthe30rar_200905/index3.html