I too hate when people steal any of my stuff, but I can say that we're lucky where we shoot in that people are pretty honest usually. We have had people lose pistol magazines and if they get picked up, they go into the stat shack. If someone comes looking for them, they are generally "right over there". What gets me is the people who don't come back for their stuff. We still have some mags that no one has any idea what they are for.
Since I reload all my own ammo, I've taken to using a brass striper that is available from hosercam.com. I know, it's from down here, but I can honestly say that if you stripe your brass, people generally leave it be and may even give you your own brass since only you have that color combo.
Vince