I was cleaning my RRA 9mm AR today. After looking into the lower and seeing hundreds of rounds of built up crud I decided to clean my lower, something I don't normally do. Anyhow to make a long story short I was wiping down the lower and noticed a vertical split running up the front of my magwell. My first inclination was that when I had reinstalled the magwell adapter I had over tightened the screw (the magwell was moving before and not seated high enough) and split the magwell, but then I started to think... is the lower that fragile that overtightening a screw in the adapter would cause it to split right down the middle? I'll see if I can get you some pics, and I'll call RRA tomorrow to see what they say.