For me, my stomach would get hard and then I would feel like someone was sinching a belt way to tight and then the pain at the belt would go away and then my stomach would soften they weren't consistently the same amount of time apart (though all between 2 and 5 minutes) and lasted about 30 seconds and no matter what I did they wouldn't go away
Your tummy should get real tight for 30-60 seconds every few min or longer depending how far apart your contractions are.