Ahhhh! Statistics!
http://www.guncite.com/gun_control_gcfullau.html
Crime with Legally Owned Machine Guns
In 1995 there were over 240,000 machine guns registered with the ATF. (Zawitz, Marianne,Bureau of Justice Statistics, Guns Used in Crime [PDF].) About half are owned by civilians and the other half by police departments and other governmental agencies (Gary Kleck, Targeting Guns: Firearms and Their Control, Walter de Gruyter, Inc., New York, 1997.)
Since 1934, there appear to have been at least two homicides committed with legally owned automatic weapons. One was a murder committed by a law enforcement officer (as opposed to a civilian). On September 15th, 1988, a 13-year veteran of the Dayton, Ohio police department, Patrolman Roger Waller, then 32, used his fully automatic MAC-11 .380 caliber submachine gun to kill a police informant, 52-year-old Lawrence Hileman. Patrolman Waller pleaded guilty in 1990, and he and an accomplice were sentenced to 18 years in prison. The 1986 ‘ban’ on sales of new machine guns does not apply to purchases by law enforcement or government agencies.
Source: talk.politics.guns FAQ, part 2.
The other homicide, possibly involving a legally owned machine gun, occurred on September 14, 1992, also in Ohio (source).
In Targeting Guns, Kleck cites the director of ATF testifying before Congress that he knew of less than ten crimes that were committed with legally owned machine guns (no time period was specified). Kleck says these crimes could have been nothing more than violations of gun regulations such as failure to notify ATF after moving a registered gun between states.
Crime Involving Illegally Owned Machine Guns
Again in Targeting Guns, Kleck writes, four police officers were killed in the line of duty by machine guns from 1983 to 1992. (713 law enforcement officers were killed during that period, 651 with guns.)
In 1980, when Miami’s homicide rate was at an all-time high, less than 1% of all homicides involved machine guns. (Miami was supposedly a “machine gun Mecca” and drug trafficking capital of the U.S.) Although there are no national figures to compare to, machine gun deaths were probably lower elsewhere. Kleck cites several examples:
Of 2,200 guns recovered by Minneapolis police (1987-1989), not one was fully automatic.
A total of 420 weapons, including 375 guns, were seized during drug warrant executions and arrests by the Metropolitan Area Narcotics Squad (Will and Grundie counties in the Chicago metropolitan area, 1980-1989). None of the guns was a machine gun.
16 of 2,359 (0.7%) of the guns seized in the Detroit area (1991-1992) in connection with “the investigation of narcotics trafficking operations” were machine guns.
Dude arrested in Oregon had 13 fully automatic weapons. Mary Jane grower. Not your typical “gang banger” . The average dummy on the street would not have anything but a cheap throw away gun.