The MK200 does not eject shells as of writing this (IIRC it did at one point a while ago) but it does produce the "shells hitting the ground" sound. So either this is a bug and the shell sound is not what is intended, or the bug lies in the issue that there are no visible shells being ejected. I don't know what the Devs' intentions are for this gun's ammo, Caseless or Cased Telescoped, but I'd wager that it is using caseless ammo based on the model and the precedent of using caseless ammo for other weapons. Therefore the solution would be to remove the shell hitting the ground sound.