Simply lifting the action bar as you describe, without removing the magazine tube, probably bent the slide arm. It may be rubbing on the slide arm cover and inside the receiver wall creating friction that causes the action to be stiff. 

Proper way to dis-assemble is to remove the magazine tube and lift the entire forearm and action slide out after removing the slide arm cover. You may be able to straighten the arm after removing it this way, but be careful. Too much bending can break the piece.