I'm not too sure Matix was firing in bursts, because it seemed to me (although the scene only shows part of his hand) that he was simply pulling the trigger quickly.

If I had to guess, I'd say it's most likely a civilian AR-15 A2. Depends on the lower receiver (if it lacks the fencing around the mag release, that would be consistent with the AR-15 A2s in production in the mid- to late-80s).

I think this might also be the earliest movie to feature A2-style guns.