History channel, or the Military channel has aired video of a single sniper popping off three men behind such a fortification with such a device. I do not know about confirmed kills, but the 3M splatter on the viewable wall behind the emplacement said much.
Not a pretty thing, but a necessary one.
I saw that show.........
Big splatter, but it was a re-enaction of the event so they may have been generous with the red paint.........