Other than wear, which it does sound like the frame has, grit or a broken part inside the action might be causing the grind and harder "shifting" of the trigger guard. Best is to take the frame apart to know for sure what it is. Gives you the chance to thoroughly clean and re-lube, check the condition of all parts, etc. Just dumping the action in a gunk bath is not a good idea as a frame is best lubricated with three different types of lube and they can't all be done without taking it apart. Other option is to send it to TC as they would replace any worn parts and clean and lube it for you under warranty. But I'd call customer service first to find out what the current lead time would be, especially if it is being used for hunting seasons. FWIW, HTH.