You're paying $85 for a semiauto carrier and 9310 bolt, and you get to put it together. You could get better specs fully assembled from AIM Surplus at the same or lower price.

http://www.aimsurplus.com/product.as...h=bolt+carrier

Other than that, it looks OK. From what I've read, there is more to properly installing the carrier key than just bolting it on.

Non-mil-spec BCGs are quite cheap and plentiful right now. And it's not an awful time to pick up a BCM or DD for slightly more money.