Ammo crisis of 2013 is quite persistent, and there has been plenty of articles on how to deal with it, such as
One Box Workout
But
Todd Green points out that it is not just the quantity that has to be looked at, but what kind of training you are doing. He proposes that it is better to focus on skills that can only be improved with live ammo and verifying your skill.
My guess is that some of the basic skills that can only be improved with live ammo are 1)follow-through and 2) transition from target to target
From: Pistol-Training