I'm now stuck with a worn carbine repeater which does stay in my inventory when I log off, but according to the gun shop I don't own one any more. I've picked up worn versions of other rifles and shotguns but they don't stay on my character if I have a decent version already. I have to conclude therefore that I haven't overwritten my carbine repeater by picking up a worn version so I must have dropped it somewhere.
You can drop weapons during a fist fight, if your opponent disarms you, but I'd assume you can't actually lose the weapon if you fail to pick it up afterwards. Has anyone tested this?