When reloading the MP5 K submachinegun the clip cannot be removed from the gun or exchanged when holding it. Pressing "R" produces no response and scrolling over the gun and right clicking doesn't show the option "Remove clip". Plastic had guard can be removed but not the ammo clip

The only work around is to place the weapon on the ground. At this point the clip can be ejected and a new clip place manually into the gun. This is rather cumbersome in a firefight.