You have the two screws in the forearm cap and the one at the end of the magazine tube. After removing all three, you have to pull the front of the tube down a little over 1/2 inch. Then the tube should come forward, Sometimes it is tough to move down the 1/2 inch because the forearm also have to move down. Sometimes the forearm is a little long and gets wedged between the receiver and the forearm cap tenon. When the is the case, you have to work the forearm down so the tube can move.
Hope this helps,
-Bob