Think I finally found the cause for this. If the weapon despawns while you are over it ( possibly while also hitting other buttons ) it seems to pick it up. The only times it has ever happened to me is with weapons that are despawning, and while I am moving.
I say they are despawning at that time because the grenades / other kit that the dead person had also disapears when the weapon is un intentionally picked up. They are not then in my inventory, so I am assuming they were despawned.
I say they are despawning at that time because the grenades / other kit that the dead person had also disapears when the weapon is un intentionally picked up. They are not then in my inventory, so I am assuming they were despawned.