Thanks fits the bill - imo. AK’s are pretty easily converted also but not for a novice, take a few skills.
If I was looking to do bad I wouldn’t use a drum or belt-fed myself, but with these nutcases, they mostly know what they see in the movies.
Something about that automatic fire at the concert doesn’t sound quite right but I have no idea what’s going on. Sounds like a heavier caliber than 5.56 though - maybe 300 Blackout.