The final thrilling chase scene... (spoilers)

I noticed in the final chase scene, when the Yamana men come out of the darkness and kill the two samurai that had been kidnapped as pack mules, that when the general, the princess and the farm girl ducked behind cover, the film would cut to the bullets hitting the cover, and then it would cut again to the trio running out of cover. It made me think that Kurosawa used real bullets to get the "special effects", and cut in footage of real gunfire when the actors were safely out of reach of being shot (i.e. over in the services truck having a snack between takes). Does anyone know anything about this theory?