I doubted it was actually a machine gun. I finally found an article that mentioned the actual gun in detail.
The model Raymond Martinez was carrying Thursday was a semi-automatic variation called the Masterpiece Arms 9-mm
The gun in question was not a machine gun. Rather, it was a semiautomatic copy of a Mac 10 machine pistol with a 30 round magazine. Bulky and awkward, poor quality and inaccurate. One shot per trigger pull. Scary looking, but virtually every modern 9mm is smaller, lighter, less bulky, more ergonomic, more reliable and more accurate. Many have available 30 round magazines.
Even the actual machine gun version is not capable of firing thousands of rounds per minute--After a few seconds to empty the 30 round magazine, the gun is empty. If you had the 34 magazines needed to fire 1000 rounds and switched them as quickly as possible the gun would overheat and malfunction before you were finished.
One of the clues was "purchased from a dealer". A true Mac 10 costs around $4000 used, requires an extensive background check and a $200 federal transfer fee. A non-machine gun copy is around $400 new.