Have you taken a look at Bernie Sanders' voting records?
Labels don't say much -- voting records do.
Sanders voted for the Iraq Liberation Act*, which Dennis Kucinich also voted for, and cosponsored** the Iran Freedom Support Act, which Kucinich voted against. That puts Sanders to the Right of Kucinich who doesn't call himself socialist.
Take a look at the U.S. Campaign to End the Israeli Occupation's ratings, too, at <http://www.vote-smart.org/issue_rating_detail.php?sig_id=003519M>: Sanders' score is +3, lower than the scores of Nick Joe Rahall (+7), John D. Dingell (+10), Lois Capps (+6), Kucinich (+8), Barbara Lee (+8), John Conyers (+7), Carolyn Cheeks Kilpatrick (+7), Fortney H. 'Pete' Stark (+7), Lynn Woolsey (+6), Maxine Waters (+6), William Lacy Clay (+6), Melvin Watt (+6), Jim McDermott (+5), George Miller (+4), Maurice D. Hinchey (+4), Donald M. Payne (+4), and many others; Sanders's score is 1 point lower than Jim Jefford (+4), whom he will replace, in fact.
* <http://clerk.house.gov/evs/1998/roll482.xml>
** <http://thomas.loc.gov/cgi-bin/bdquery/z?d109:HR00282:@@@P> -- Yoshie <http://montages.blogspot.com/> <http://mrzine.org> <http://monthlyreview.org/>