We just don’t know!
The answers came Sunday from the inspector general’s office, which found major discrepancies in American military records on where thousands of 9-millimeter pistols and hundreds of assault rifles and other weapons have ended up. The American military did not even take the elementary step of recording the serial numbers of nearly half a million weapons provided to Iraqis, the inspector general found, making it impossible to track or identify any that might be in the wrong hands.
Exactly where untracked weapons could end up — and whether some have been used against American soldiers — were not examined in the report, although black-market arms dealers thrive on the streets of Baghdad, and official Iraq Army and police uniforms can easily be purchased as well, presumably because government shipments are intercepted or otherwise corrupted.
In a written response to the inspector general’s findings, the American military largely conceded the shortcomings.
U.S. Is Said to Fail in Tracking Arms for Iraqis (New York Times)
Thoroughly unrelated weaponry news: US is only country to oppose UN arms trade treaty (Telegraph)