Yes, I agree with all that Mike posted above. It all depends on the 'how much'. I have never had any real success with stretching a hat anything more than nudging it out slightly. AND I have experienced much failure. ....such as distorting the band area so the stretch shows, popping the sweat stitches. The only success I have really had in resizing a hat is sending it to my hatter for a reblock and resize. With the ones I have just eased out I need to leave the hat jack in the hat as a band block or the sweat just reverts to its original sizing.