Talk to the range management. Many indoor ranges don't allow for the picking up of brass, especially in front of the shooting stations. Others will allow you to pick up only that which falls on the shooter's side of the stand. Management may allow you to pick up brass in front of the stand if you are the only one there or at certain times. One I know of sells the brass back at a very reduced price for members instead of allowing them to pick it up. The only other advice I know of is to take a step back when you shoot. Maybe fewer empties will make it to the other side of the station.