根据 Wikipedia, By 3 p.m., Severloh had fired approximately

12,000 rounds with the machine gun and 400 rounds with the two rifles. 

The American GIs had poor tactical positions during the storming of the beach. Between the edge of the water and the dunes, there was a very wide, treacherous strip of sand to cross, which was completely flat and without cover...Severloh’s lines of fire almost entirely covered the sections of beach known as Easy Red and Fox Green