I decided to remove the buttstock to change the cast/drop spacer today. The directions said to use a 15mm socket to remove the nut on the stock bolt. That was the wrong size for my gun. It was a 16mm nut.

Stock removal was actually quite easy once I had the correct size socket (16mm). You need a fairly long extension to reach the nut. I would estimate about a 9" or 10" extension would do. Beneath the nut was a lock washer and a flat washer. If there was any plate below that, I didn't see it because it must have stayed inside the stock.