For those who have never held a gun or loaded a magazine, dummy rounds are a great tool for safely learning the process. Using live ammunition to teach a new shooter how to load, chamber and clear a firearm is not ideal. Perhaps one of the simplest and most versatile training tools that firearm instructors can use are dummy rounds or Snap Caps. But they have a far more reaching purpose than just in the hands of an instructor for dry firing. Dry firing is simply pulling the trigger of a firearm without live ammunition in the chamber. Since the chamber is empty, nothing will go off and hence the shot is "dry".
Snap Cap is a name originally trademarked by the company A-zoom. But it is used generically for any inert cartridge-shaped device with the same shape and size of a real cartridge. Snap Caps do not have a powder charge, real primer, or projectile. Dummy Round: An inert training device, made when the primer and powder charge is removed from a real cartridge. Both terms are interchangeable. Why would you dry-fire your firearm? I would say ammo is not cheap nowadays. If you are competing in shooting sports, nothing and I mean nothing can beat spending time at the range for some practice sessions. But that will cost you a lot of money.
Today, with 3D Printing we are able to cut down the cost for low caliber dummy rounds. 3D printing or additive manufacturing, is the construction of a three-dimensional object from a CAD model or a digital 3D model. So far we've been able to manufacture 9mm, 22lr and 762x39 rounds found here.
As always, follow the necessary safety precautions when handling firearms. It's loaded every time you pick it up unless after you checked the chamber. Make sure that you are using the dummy rounds or snap caps and put away all the live ammo before you begin dry firing. You can never be too safe!