After server connect with rifle on back and other rifle in hand I cannot change the gun anymore. Pressing the shortcut-numbers doesn't work, dragging in hand doesn't work, menu doesn't show anything but "Inspect" on every item.

If you put or throw the gun away, it just disappears for the moment. Still not possible to take anything in hand.

I've experienced this in 0.57 experimental very much.

Connecting to another server is the solution to all of this problem. The rifle is back in hand, the shortcut numbers do work, the menu shows "Take in hand" and so on...