It's already getting too late.......I gotta crash. I'll pull one of my bolt carrier's tomorrow to put up a pic. Just about all of my Armalite carrier's have the "grooves" in them. Except my original A2 carbine. It was smooth (the carrier). And the exterior of the upper didn't have the FA. I'm not 100% sure. But I think shortly after I bought my original A2 was when Armalite went to putting the FA on just about most of their rifles. Hell, they don't even offer A2 style uppers anymore. Yeah, yeah......laugh at me. I still like the look of the original "Eugene" design w/the fixed carry handle. Not that a flattop doesn't have a place in my heart either.