Yea, that is not cool. Knuckleheads are doing something stupid and dangerous, besides illegal in the Mojave National Preserve. What goes up must come down.
In Mojave you can't go shooting. Paradoxically, you can hunt. You can shoot a gun if you're legally hunting with a hunting license, in season and per the Cal F&G rules. F&G laws dictate you can't shoot within 500 feet of a road or trail or at night, among other things. But there isn't much to hunt in Mojave because wildlife is pretty sparse out there. Mule deer could be a legal species. And I suppose the non-native wild burrows might be legal, but who would hunt for burro or mule?
We camped and 4wheeled by Calico Ghost Town (Barstow) a couple of months ago and the sad part of that place is that people go out there in part to shoot guns. They shoot at cans, bottles, old junk - and they leave it all there along with shell casings. We camped out beyond the crowds and everywhere I walked there were shell casings, metal and broken glass. Shooting bottles is really stupid because there's no good way to pick it all up and it will last forever, until the desert sandstorms grind it down. People should take paper targets or even wood, which will disintegrate over time if they leave it. Or become firewood.
In the desert everything happens slowly, like plant growth. Even stick lumber takes forever to degrade. That's why there are still 130 year old mining ruins, cabins and wood chutes, that are still intact.
If you look for books by Death Valley Jim you'll find a book on Mojave. He describes some of the petroglyphs and pictograms you can find there. The Indians have been there for over 1000 years, as I recall. They inhabited the land as recently as the 1880s.