The cornerstone of his package is a call for universal background checks for gun buyers, some version of which seems to have a stronger chance of moving through Congress. Currently, only sales by federally licensed gun dealers require such checks, which are designed to prevent criminals and others from obtaining firearms.
Feinstein's bill would ban future sales of assault weapons and magazines carrying more than 10 rounds of ammunition but exempt those that already exist. It would bar sales, manufacturing and imports of semiautomatic rifles and pistols that can use detachable magazines and have threaded barrels or other military features. The measure specifically bans 157 firearms but excludes 2,258 others in an effort to avoid barring hunting and sporting weapons.
Feinstein, who helped create a 1994 assault weapons ban that expired in 2004, and other supporters cite studies showing use of the firearms in crimes diminished while the prohibition lasted. A 2004 report said the proportion of gun crimes involving assault weapons dropped by up to 72 percent in five cities studied.
Opponents cite data from that same study showing assault weapons were used in only 2 percent to 8 percent of gun crimes, arguing that a ban would have little impact. The study also estimated there were 1.5 million assault weapons owned privately in the U.S. in 1994, and an estimated 30 million high-capacity magazines as of 1999, which critics say means exempting them would diminish a ban's effect