What is the primary function of the cleaning brush used on the M16A3/M4A1?

The primary function of the cleaning brush used on the M16A3/M4A1 is to remove carbon buildup. When the firearm is discharged, residues from the propellant and the primer, including carbon, accumulate in various parts of the weapon, particularly in the barrel and the chamber. The cleaning brush is specifically designed to scrub these residues away, ensuring that the internal components can function properly and that accuracy is maintained. Regular brushing helps maintain the rifle's reliability and longevity by preventing buildup that could lead to malfunctions or degradation of performance. Proper maintenance, including removing carbon buildup, is essential for any firearm to ensure it operates smoothly and safely.