This makes sense. Mexico uses the Colt Automatic Rifle (the automatic rifle that has been marketed by Colt for many years) and they seem to be fond of high-capacity drum magazines like the Beta C-Mag.
The Colt IAR is the only IAR competition entrant I have personally shot. It shoots just like a normal AR-15, albeit a heavy one.
[ Many thanks to SpanishInquisition for posting the link. ]