Most of the action shooting sports, IDPA, IPSC, Bianchi, etc. require that at the end of your run, you "unload and show clear". eject the mag, lock the slide back, show R.O. empty chamber. After that, the next instruction is usually, "slide down, hammer down, holster". Just like it sounds, let the slide forward, pull the trigger, and return the gun to the holster. The pulling of the trigger is to be certain there is/was nothing in the chamber before going into the holster. Statistically, more negligent shootings occur during holstering/reholstering. As for the sports involved, and the scoring that accompany them, if, when you pull the trigger the gun fires(because there was still one in there that the R.O. didn't see), you are deducted points for failure to make safe. So by pulling the trigger to release the firing pin by whatever means the gun uses, there is no doubt that there was nothing in the chamber, since no loaded guns are permitted off the firing line/shooting stage.