I was thinking about getting a Carbon framed AR. Anything I should know?

SLM

First off, it's not really carbon fiber. Second, it is unique to one company.

That being said, I know nothing about them. I saw one at the Oregon Arfcom shoot last weekend that bumped like nothing I've seen. It was a Carbon-15 pistol.

I fired a a few magazine's worth of ammo through my nephew's Bushmaster Carbon 15 rifle. Seemed okay, although with that thin barrel the handguard heated up fast and stayed hot to the point of being uncomfortable, at least more so than I am accustomed to with my typical AR rifles and carbines. I also didn't really care for the considerable number of proprietery parts. But it functioned okay, appeared accurate, and my nephew likes it's light weight and ease of handling.

I bought a Carbon 15 almost a year ago...I have never had any problems period. It is a reliable gun and
Bushmaster is a great company with great customer service. I use my Carbon 15 for Coyote hunting and it sports an Eotech. I can consistantly hit a 12 x 12 steel plate at 300 yards off-hand.  Not sure what else to say...