Caleb,
It's been awhile since I've removed an M37's buttstock, but rather than use a screwdriver, a 12 point socket will fit over the square bolt's end. It's a lot easier to apply torque to the socket than with a flat bladed screwdriver which will tend to slip out of the notch. I don't recall the size of the socket, but while the bolt is out, you can "trial and error" for fit. Gil