So I finally got around to watching
Halo 4: Forward Unto Dawn, and while all the weapons in the actual film were just cast resin replicas (which were cool in their own way) it appears that they actually used real QBZ-97s for a boot camp they put the actors through. I thought it was odd, A) the weapon choice, and B) they actually had actors practice firing weapons even though they'd only be using cast replicas in the actual film.
