Professional Ordnance is the maker of the true Carbon 15, there rights were bought by bushmaster, and they still continue to make them for BM still to this day. It is a mixture of Carbon, Kevlar, and Armids.
I have personally owned and shot 5 different models. I have never once had a problem with any of them, and they now are interchangable with mil spec parts. They are cooler (temp wise), lighter, and more economical. I have built them in 7.62x39, 6.5 grendel, and 223. They have held up fine after thousands of rounds.
The only issue we had, was one bulit into .50 Beowulf. It tore the threads from the reciever, were the buffer tube inserts into the reciever. But then again, I have killed two red dots and one scope on the Beowulf too.
The reason they are cheaper, is not quality, it is speed, materials, and labor that brings the cost down. I wonder how many people that bash them own Glocks??? Did you know a Glock only cost $2 in raw materials.
Glocks work just fine, and they are tactical tupperwear. Why can't a AR15 me made of the same thing? I admire Professional Ordnance for thinking outside the box, and trying something new.
If you don't think carbon is way to go fine, but you are now starting to see the military pick up the ball and run with it. Take a look at some of the lastest combat rifles to come out and see what they are made out of.
HK ump, HK sl8, G36, FN p-90, FS 2000, Kriss Super V, wow these must all be junk to with there poly/carbon construction??
Schooled, go back home with your tail between your legs.