I just bought a new lower which I thought was new, but I'm not sure. It was a complete lower with a 3-position stock. It was $280 which I thought was a good price. Anyway, the entire reciever is very dry, with almost no lubrication. The moving parts do not move smothly like my previous AR, the tigger, mag release, etc are gritty as well. There are a few small white specks, as if the finish was chipped off. Is this normal for a new lower? And who makes 3 position collapsable stocks? It is kind of cheapy feeling, but I thought it would be easier to buy a new stock if this one was really bad, where it would be hard for me to find a lower anywhere else any time soon. Also, how can I found out when the reciever was made by the serial number?

Two good places to look for wear.
The bottom of the mag well will likely have scratches around the edge/bevel where magazines scratch it up when being inserted.
Also, the inside walls, where the upper lug (? term) gets pinned in.  The lug tends to rub the inside wall a little bit from being opened and closed a lot. (just over where the rear shelf is)