Check the area around the breech seal and where the seal contacts the action port. If there is evidence that air is leaking,..you will see it most of the time. A properly working seal will leave a distinct "O-Ring" mark on the action,....if you're experienceing air leaking through or around the seal,,...this mark will look to be 'blown" out to one side via escaping compressed air. Evidence that there is a problem!! Try the tissue paper trick if you don't see any visible signs. tjk