I have three of their uppers, a 16", 10.5", and 12". All in 223 (wylde chamber). They are great uppers. I usually run them with a can and they are great due to the adjustable gas block. I have been eying a 300blk upper from them. I don't know why they stopped making the 9". 12" seems a little long for a 300blk for me at least. The mod1 changes improved an already great upper. They have great customer service. My experience is because I directly ordered my uppers from them due them offering a nice military discount. I don't believe they sell directly to individuals anymore though. they are quality made and I am sure you will love it once you get one.