Ted, are we still talking about the M220, not the over under .22/.410? If so, on the M220, put the screw back in place. Assuming you are right handed, with your left hand, hold the barrel just above the tip of the forearm securely, then with your right hand, grip the forearm near the front toward your left hand and pull out and downward and the forearm will release from the barrel.
Now to remove the barrel, again, holding the pistol grip in your right hand, move the top lever as far to the right as it will go. This will open the action and the barrel can then be moved slightly to the rear of the action with your left hand and it will come loose from the pivot pin and separate completely from the action.