Whenever i try reloading a gun by holding down "R" the magazines get glitched. By that i mean if you try to take the mag that got swapped in your hands to reload it with bullets it won't work. So you simply get stuck with a mag that you can't reload or empty if you have any ammo left in. This can be fixed by logging out and in again but it gets extremely annoying being forced to swap your mags by accessing inventory instead of just pressing R.
Another thing would be that if you try and drop it on the ground it will make it impossible to pick up again. And also after relogging the mag just dropped got placed back in the inventory.

This happened to me with all weapons that i tried using, modded or vanilla.