Ok I agree with you that they don't quite looks like hardened SF Warriors. However wouldn't actors be using blanks in their weapons? Because If you look at this picture those rounds defiantly don't look like blanks, to me anyways...
Also that weapon looks like it has actually been used. I don't think many movies would take that much time to make an extras weapon look that weathered. However in saying that her gear looks brand new. So I really have no clue.