When you fire a weapon with a blank there's less kickback (to the point where you'd notice the difference in recoil based on what you braced for vs what you got). At least, on all the weapons I trained on. Could depend on the weapon I guess though.

I didn't mean to say it wasn't a thing, just that given what I have experienced I feel like you'd know if you'd shot a blank or not. It might psychologically make pulling the trigger easier but I don't think it changes the end result.