I was watching Hickock45's video on trigger control, which is pretty good:
My tip on trigger control is at http://jumpthestack.blogspot.com/2010/12/trigger-control.html
and he mentions doing the ball and dummy drill, in which you load a number of live rounds and dummy rounds into a magazine in random order and detect flinching when you drop the hammer on a dummy round. That drill is very useful for detecting and correcting problems with your trigger control.
He mentioned that he hand loads some dummy rounds with no primer or powder for use in this drill, rather than using commercial snap caps. This is a great idea. I wouldn't want to use relatively expensive snap caps for this at the range because there's a good chance that they'll get lost. Also because commercial snap caps look and feel so different from real rounds that if I was loading the mag myself, I would know which ones they were.
I generally had not been interested in loading dummy rounds myself for use dry firing at home because I was afraid that I might accidentally load a live round and not know the difference. But for the purpose of this specific drill, the dummy rounds would only be used at the range while pointed at the backstop anyways. And when I load them into the mag, if I don't specifically look at the primer, I can't tell them from live rounds so they are more likely to surprise me and reveal my flinch. If you don't reload, an alternate option is to use snap caps but just mix live rounds and snap caps in multiple magazines and put the magazines in a bag and shuffle them and pick a random magazine.