Actually, I got one of those when I got the gun. When I got home, I found a flyer from Hi-Point in the box stating that use of ProMag mags would void the warranty.
*sad trombone sound*
I have an Centurion UC-9 carbine that I really like, but I haven't had a chance to shoot it yet. I did get eight (8) extra Uzi 32-round magazines for it though.