Here's what I did:

I had a AKM in my hands (inventory was full) and logged off.
The next day, I logged in and discovered that I no longer had the AKM in my hands (weapon was gone).

Walked around and ran into a binocular. I took in into my hands (inventory still full) and then my AKM (exactly as I had it, with attachments and ammo level) appeared on the ground where the bino was. So the binocular had replaced the AKM in my hands.

The bug: when you log of with the AKM in your hands (note, NOT in your inventory) it's gone when you log back in, but IT STILL there... you just can't see it.