On a standard mech, the machine gun module mounted on its chest hardpoint would have been classified as a light or ultralight weapon system.
Enemy mechs wouldn't have taken such a small and weak weapon seriously. Its rounds were too light and the firing mechanism could not propel them forward at impressive speeds.
The chances that a small machine gun module could penetrate the armor of a mech was practically minimal. The only chances they could inflict meaningful damage was if they struck the internals of a mech, but more powerful weapons could do that job even better!
One of the few advantages of a light machine gun weapon system was that it took up minimal capacity. The requirements were low and their small caliber allowed a mech to carry a lot of ammunition. Their firing rate could also be high.
This made them suitable for attacking lighter targets at a distance. They excelled at clearing infantry, shuttles and unreinforced structures.
