Sen. Dianne Feinstein’s, D-Calif., most famous piece of legislation, a ban on so-called “assault weapons,” was far less effective than she and the gun control crowd claims it was, according to a report released this week by the nonprofit ProPublica.

The ban, which was passed in 1994 under President Bill Clinton, expired 10 years ago. However, spurred by recent mass shootings in Newtown, Conn., and Aurora, Colo., Feinstein has been keen to see the U.S. Senate to reinstate her signature piece of anti-gun legislation.