The Sherman's shot bounces off, so there's not even a red flash on the gunsight and thus following up with another shot immediatly thereafter... hmm... a spot is a possible explanation, but unlikely. You would have to aim very carefully in order to not to hit any trees on the way, even if there was no fog. Plus it still does not explain why he instantly follows up with another shot as soon as he has managed to reload - after all, since he did not get a hit indicator he couldn't know whether the shot bounced off or if the spot was simply inaccurate. Blindfiring into fog out of FFFFFUUUUUstration, or seeing a marker on the map and approximating the firing angle and getting a lucky kill is one thing, shooting down a winding road and scoring a hit twice on a moving target is another.