Does anybody know how to take down the semi-auto version? Instructions say remove takedown pin (did that already). With 1 hand, press forward on receiver, at the same time carefully lift barrel with the other hand. I can get the barrel/receiver to move forward only about 1/32", just a wiggle really. The barrel shows no sign of lifting up & away from the stock. It all sounds simple enough, but not working the way it should. Who can advise me?