So one of my friends here in OKC got an AR and he noticed a white powdery substance on the outside of the magwell on his lower. Said it wipes away with CLP but will randomly come back. Any ideas? I've searched the Internet and haven't come up with anything quite like this. I'm not going to get into brands or manufacturers because I don't think that this is anything that would require sending back nor do I believe it has anything to do with who manufactured the lower, more so te environment it's being stored in. The rifle is kept in a safe when not in use. If you look, you can also see it in the dimples in the front of the magazine.