If your magazine (or gun or any other equipment) falls while you are shooting or reloading, let it fall. People tend to swing the gun backwards and muzzle those behind them if they panic and try to catch the mag or pick it up with gun in hand. First set the gun down first and then bend down to retrieve the magazine.
Whenever you are holding a firearm, whether loaded or unloaded, it is imperative that you keep it facing a safe direction. More specifically, you must obey the 180 Rule. The muzzle of your gun may NEVER break the 180-degree plane — the imaginary line that extends to your left and right on the shooting line. If you pivot your body, the line doesn’t move with you. It stays anchored to the targets and parallel with the back of the berm.