I see cops mislabel firearms alot, but I understand that not everyone is into learning about guns as much as we do. Some of them just learn and train with the guns they have to use. I know one cop I was talking to told me he really wasn't into guns and it was just part of the job. I get more bothered by military troops in areas like Afghanistan mislabeling their collected small arms as I think they should be more familiarized with them.
I understand that they shouldn't be expected to know every firearm out there. However, if you aren't 100% sure what it is then why not just call it a "Semi-auto rifle" instead of saying AK-47 all the time.