A hand guard adapted for use in a firearm having a barrel and a line of sight in a sight plane. The leg spring is constructed as a double leg spring with a middle double leg of two parallel leg arms, protruding between two groups of spring coils from, in each case, one of the inner spring coils, and two outer legs, protruding from the in each case outermost spring coil of each group. To overcome the performance degradation due to the differential capacitive load, an active negative-capacitor circuit cancels the effect of the large input capacitance of the ADC comparators. A metal layer is formed on the side walls inside the through slot.