The nation's police chiefs are finding an alarming increase in criminals' use of assault weapons — the high-powered battlefield rifles that used to be banned, back when the federal government showed greater concern for public safety.

The 10-year ban expired in 2004, despite the vows of presidential nominees from both parties to fight for renewal. Congress hasn't mustered the guts to try, preferring to roll over for the gun lobby.

A survey of more than 130 local police chiefs and officials found 37 percent reporting an increase in assault weapons in street crime. Front-line police find criminals generally packing more powerful heat, with more than half of the chiefs citing increases in large-caliber handguns and high-capacity semiautomatics — the real-life stuff of tough-guy movie fantasies.

Miami police reported that four years after politicians allowed the federal ban to lapse, homicides by assault weapons increased sixfold, including the murder of two police officers.

The findings were part of a police brass “summit on guns and crime” in Washington last November that was studiously ignored by the capital ruling class. Meeting as members of the Police Executive Research Forum, the attendees underlined the disheartening fact that “there seems to be little or no appetite for gun control legislation in the U.S. Congress or the Obama administration.”

In their frustration, the chiefs deserve credit for trying to come up with some local and state solutions — for example, requiring owners to immediately document lost or stolen guns as a deterrent to the current dodge of selling them as “lost” in the underground market.

The chiefs were collectively enlightened, discovering that in most states gun dealers are monitored not by state or local police but by federal firearm inspectors. They have a force of but 600 covering 115,000 gun dealers — who may be visited no more than once a year. Polls regularly show that the public, including most gun hobbyists, wants more realistic gun controls. But don't tell that to the timorous politicians of Washington.