They aren't necessarily underused, it's that people just don't want to find the time to try other guns. It kind of boggles me that the majority of players in this game camp requiring little mobility, yet an LMG offers a larger clip, high damage(40 close, 40 far 3 shots)(SP 56 close-56 far 2 shots), and with sleight of hand the reload time is fast. With the addition of lightweight(since stopping power isn't really needed), player's can have the same mobility as someone with an assault rifle. The gun also has relatively little recoil. When I had the game I was sniping people from across the map with it. I think the primary reason is that players don't think strategically. They use what works and don't consider anything else. That's why the 1887's and the FAM16 are so popular.