There was a booth set up today at the local gunshow where they were selling stocks for Glocks. They sold the stock as a complete package with the stock and a 16" barrel. The barrel looked somewhat strange, although, it pointed quite well. It would be fun to use for target shooting (albeit somewhat awkward).
The kit also came with a solution for the long barrel which is all of the paper work that you need to apply for an SBR permit. Once you get the permit then you can put your normal barrel back in when you are using the stock.
Overall I liked the package. The stock fit my shoulder really well. It seemed very solid and well built. I think that the company which sales them is called "Denny's Stocks." In fact I think I was talking to Denny today.
I would have bought one, except that they don't have any stocks for the Glock 21, or the Glock 19 just yet. The current stock only fits a full sized, Glock 17 or one of its counterparts.
If the stock is ever produced for a Glock 21, then I will buy one for certain (or if I ever pick up a Glock 17). Overall, I liked it.