not quite sure why people are suggesting to use a smaller socket, ermmm cossie head bolts are a milti spline head not a normal bolt type so wont do much good

As a few people have said mate if the heads coming off then the swarf can be cleaned out after, its best to give it a good freshen up anyway if you've got it off and deff worth checking if its warped or not, depending which bolts are stuck if they've been left in the head then its had un even pressure left on it if you havnt put the other ones back in!