First: I am honestly surprised that none of you noticed that a CHICAGO newspaper actually reported that Mayor Daley was not only lying but assault weapons aren't to blame for everything:
But last month, a Daily News review of federal firearms statistics suggests the number of assault weapons seized from Illinois criminals is not on the rise. Nor is the number of homicides committed with rifles in the nation. And rifles have been responsible on average for 15 percent of officer deaths each of the last six years.
Second: I am all for a department getting ahead of the power curve to stop streat crime. I just find it absurd that Chicago of all places is getting M4s when it wasn't six months ago Mayor Daley was trying to get everybody to turn in thier personal guns and saying that Heller means nothing to him.
Most dept's I have worked around/with the M4 type weapons aren't general issue or they are qualified with in lieu of or addition to the shotgun. The officers have the option. No one WALKS with it, it's in the trunk of the cruiser. (This isn't Europe!

) When I ran the range we qualified everyone on the M9, M16, and shotgun no matter what. Range staff also qualified M11 (Sig 228) and M14. Everyone on patrol had an M9 and a couple had shotguns on shift. The M16s were only broke out for higher security levels so most Patrolmen didn't handle it much. It showed on the range but everybody eventually qual'd.
TAB: The officers in North Hollyweird HAD access to slugs for the shotguns but didn't use them. Yes the shotgun slug would have slowed/stopped the two robbers but they were pinned down to far out to be effective. None of those guns were purchased at the time, B&B Sales GAVE the LAPD the rifles but charged them afterward. I talked with the owner while I was still in San Diego.
Problem with the 9mm AR is the round doesn't have the energy or velocity, even through the longer barrel, to stop armored (happens more and more) assailants. Also 9mm punches through walls and bodies with enough energy to hit a bystander while 223 tumbles and dissipates faster so less penetration. If you hadn't noticed that is why most SWAT guys have moved away from the MP5 to the AR over the last ten years or so