The AFF Universe Wiki also has an article on this topic: MGA Infantry Weapon

This long, sturdy weapon makes up for its relatively weak punch with a rotary barrel that enables incredible fire rates. The drawback from this, however, is that it takes a short moment for the barrel to reach its peak RPM. When actually at peak RPM, it has excessive recoil that can be near impossible to manage: resulting in rapid loss of accuracy at longer distances.