I don't think you have to remove the forward screw to get the buttstock off.
You have to first remove the rear tang screw and, of course, its locking screw (these are located at the rear of the trigger plate on the underside of the gun). Then pull the stock rearward to take it off. The manual says that it you still have trouble taking it off, then remove the trigger plate pin and its lock screw (these are located on the left side of receiver slightly forward and above the trigger guard). The trigger plate pin is removed by driving it out from the right to left side of the receiver using something like a punch to drive it out. Once the pin it out, release the carrier by pressing the carrier latch button, then press the forward end of the trigger plate upward slightly into the receiver.
If the gun is really nice, you might not want to risk breaking something or buggering up the screws.