I've had an AR on my mind for a while, and I'm still trying to figure out which brand, but I do know I'd like to have a bull barrel. I just which I could have one in a darkened finish.
If the rifle you want has a stainless finish barrel you could have it painted. Duracoat is bullet proof and affordable. Alumahyde is down right cheap, DIY, a little time consuming for the drying process.