I believe there have been a couple that was publicized, and if I remember right, the more prominent one, was by a cop.
I personally knew someone who shot up his neighbor's house with one (Ruger AC556), was arrested and did some time for it, but for some reason, nothing about the gun ever came out or up as I remember.
I personally knew someone who shot up his neighbor's house with one (Ruger AC556), was arrested and did some time for it, but for some reason, nothing about the gun ever came out or up as I remember.