Shooting the 15-22 today, and had a round fire out of battery. Blew the extractor out.
Had about 2k rounds without cleaning, the bolt face and end of the barrel have a lot of build up on them. I am sure that it had something to do with it. So if you haven't had this happen to you yet, make sure you keep it clean.
Now I get to call Smith tomorrow and see about getting a few extractors sent my way.
edited to add: Thats another reason to always wear safety glasses too.