It's obvious once you pull the stock, Its been a while, but I seem to recall a rollpin. To remove the through bolt I visited the hardware store and got a 3/8 drive, 3/16 bit, and used a 3/8 extension and handle. It takes a good bit of torque to break loose, and to pull the stock back into place when reinstalling.

The clearest way into the universe is through a forest wilderness.
-John Muir