Something I have noticed on the standard servers, is that lets say you load a Mosin with 5 bullets. You fire off one bullet and then try to load another round into the gun. You get a message saying that it is full. Instead you have to unload the entire magazine and then load 5 back in. As far as I am aware, you can load the extra bullet with no problem. This max be fixed on the experimental servers (not played there yet)