Please do NOT use an empty/spent case w/ projectile seated as a training/practice round.
IMO this is just an accident waiting to happen - might be lighter in weight, but will look the same. No, no, no! To me that is like taking the firing pin out of one of two identical guns with the intent of using the pinless gun for training.
Did I say don't do it?
Many guns are said to be safe to dry fire - I don't however. Think that a struck primer would offer little to no resistance to the firing pin in any event.