Sanders, unlike anyone else running, voted for the 1994 Violent Crime Control & Law Enforcement Act

[Sancho]

17. Bernie also has not been a progression on gun manufacturer and control legislation...

http://www.slate.com/articles/news_and_politics/jurisprudence/2015/05/bernie_sanders_on_guns_vermont_independent_voted_against_gun_control_for.html

But before liberal Democrats flock to Sanders, they should remember that the Vermont senator stands firmly to Clinton’s right on one issue of overwhelming importance to the Democratic base: gun control. During his time in Congress, Sanders opposed several moderate gun control bills. He also supported the most odious NRA–backed law in recent memory—one that may block Sandy Hook families from winning a lawsuit against the manufacturer of the gun used to massacre their children.

But his voting record paints the picture of a legislator who is both skeptical of gun control and invested in the interests of gun owners—and manufacturers. In 1993, then-Rep. Sanders voted against the Brady Act, which mandated federal background checks for gun purchasers and restricted felons’ access to firearms. As a senator, Sanders supported bills to allow firearms in checked bags on Amtrak trains and block funding to any foreign aid organization that registered or taxed Americans’ guns. Sanders is dubious that gun control could help prevent gun violence, telling one interviewer after Sandy Hook that “if you passed the strongest gun control legislation tomorrow, I don’t think it will have a profound effect on the tragedies we have seen.”
------------------
Unlike the 1994 Act, this is one bill that is difficult to understand after Sandy Hook.