DayZ standalone, reproducible bug.
So I'm a lefty and I reassign most of my keys. Reassigning keys, however, doesn't get rid of the bug.
I'll be chilling with my mosin and long range scope, looking out over the Berezino body piles or the Svetlo sniper perches, zooming in and out, when I'll (almost at random) up and throw my gun over the cliff and down the hill. It occurs only after pressing (or holding) zoom out, and NOT zoom in.
Unassigning or reassigning the "throw item" key does nothing. Nor does reassigning the zoom keys. It doesn't occur every time I zoom out; it only occurs when I zoom out.
It was very amusing the first few dozen times it happened. Now it's a bit of a drag to go running for 5 minutes to the railroad to find my gun.