Loot would include spent casings scattered around and in trash barrels. Sometimes a corpse or three with guns and unfired ammo.
Would have a chance of spawning within 10 tiles of any town, increased chance if nearest town has 2 or more gun stores.
Sometimes spawns next to roads, in which case they may have some nicer facilities including bathrooms, kitchen, lounge area, and possibly a small gun and/or ammo store.
Otherwise, they would spawn in the woods, and have only a porta john. This kind of shooting range would have an increased chance of spawning in the general vicinity of an LMOE shelter.