It helps to offer the summary tentatively and create space for people to correct you if you get it wrong. Use phrases such as: “What I've heard people saying so far is... Did I miss anything out?”, “Am I right that your main concerns are...?” A summary carries more weight than an average contribution to a discussion, because it should represent the views of more people than just yourself. Therefore it is very important to give people the chance to correct any biases towards your own perspective! Not to mention helping you out with things you forgot.
Some people find it helpful to take notes as the discussion happens. This makes a succinct and accurate summary much easier.