The Brady Campaign is an advocacy group that works to pass gun-control laws and advocates policies such as increasing background checks and eliminating legal loopholes that may contribute to gun violence. The organization assigns members of Congress a “lifetime score” based on how they voted on gun-control measures. Below are the group’s most recent scores, which are from 2003. Spokeswoman Becca Knox told ProPublica that the Brady Campaign does not have updated scores, and she could not provide a date for when they will be updated.

The National Rifle Association, with as many as 4 million members, is the nation’s largest organization devoted to defending gun rights and the Second Amendment. Its lobbying wing ranks lawmakers based on their support of the "right to keep and bear arms." The group’s “A” through “F” letter grades are based on how voting records, public statements and responses to a questionnaire line up with the NRA's own positions. Hover over each letter to see the group’s grading criteria.

The National Rifle Association’s lobbying wing spent more than $2.2 million lobbying members of Congress in 2012, according to the Center for Responsive Politics. Together with its political action committee, the group spent more than $5.8 million on ads and communications advocating allies running for Congress and opposing those supporting gun-control measures in the 2012 election cycle. The NRA is also considered to be one of the country’s most effective groups at motivating members to vote on a single issue. The lawmakers (and affiliated leadership committees) who received money from the NRA over the 2012 cycle are shown below.

In 1994, Congress passed a law that in part banned the sale of certain semi-automatic weapons, dubbed “assault rifles,” to civilians. Shown below are the current members of Congress who voted on the 1994 ban, which expired in 2004.