In 1994, Romney supported the Brady Bill as well as the federal ban on assault weapons. He remarked that, “That’s not going to make me the hero of the NRA.” In 2004, when the federal ban expired, then-Governor Romney enthusiastically signed a permanent ban on assault weapons in Massachusetts.
http://amspec.org/dsp_article.asp?art_id=11120
Repeating a falsehood doesn’t make it true.
Massachusetts AWB was passed in the 1990s and was never set to expire. Romney didn’t pass the AWB.