The thing that got me noticing it was the pump shotgun. I have never been in the military but I have fired an M16, AK47, Mossberg 835, and various and sundry others. I have never heard a mortar fired but in the game, the pump shotgun sounded a bit like the Hollywood version of mortars....at least to me.

"A fanatic is someone who can't change his mind and won't change the subject" Churchill