"The X1 LMG provides a Juggernaut with a strong automatic weapon and improved anti-air capability" In-game Description.
The X1 LMG is somewhere between Raider's NJ4 SMG and Doombringer's Chain gun. It deals similar damage to the NJ4 SMG, has a larger magazine, and also has a brief spin-up time. The weapon is fully automatic with a high firing rate. It is not a hitscan weapon requiring players to lead moving targets.
The X1 LMG is an excellent weapon for both indoor and outdoor combat. Indoors, this weapon gives the Juggernaut an option that prevents self-damage in close quarter battles while outdoors, it is more effective at range than the Spinfusor MKD. Taking the Spinfusor Disc as well mean that the Juggernaut still can the capability to deal explosive damage without the cumbersome Fusion Mortar.
The X1 LMG has a relatively short effective range, due to its spread and screen-shake. The best way to counter this powerful automatic weapon is to keep moving, and engage with medium range and accurate weapons, such as the Assault Rifle or the NJ5-B SMG. Spinfusors, unless you have perfect aim with it and hit every shot, are not recommended.