We said the ammunition carried around by the actors playing soldiers was made of wood, but we didn't say anything about the guns. They were as real as real gets, and all of them were time-appropriate for the film. Not only that, but the sounds they made were real, too. The sound engineers were given a very unusual task when they were making this film!
In order to achieve the gunfire sound effects, Spielberg arranged for World War II era guns to be located, fired and recorded for authenticity. Therefore, every time you see or hear a gun being fired on screen, you're also hearing exactly what it would have sounded like on the battlefield; real guns, making real sounds. When directors go this far with a labor of love, the results are usually incredible. Spielberg's obsessive attention to detail drove this movie to the point of greatness.