I doubt you will see much of a difference between magnum and standard primers.
Years ago when I started reloading, I accidentally substituted Hodgdon International Clays for Universal Clays. Nothing really bad happened except when I shot the rounds they were hot! When I got home and double checked everything I realized my mistake.
I can see the level of powder (Dillon 650) in my 9mm rounds as I load them and as long as there is powder, I drop a bullet to be seated.