I got this video from a range buddy. It's a high quality video from a professional reloading company explaining that it is SAFE to substitute small pistol primers with small pistol magnum or even small rifle primers. It also discusses primer cup strength and weak springs etc etc. This guy shows all the correct pressure testing data, AND actual range/velocity testing data to demonstrate the safety. It's about 10 mins. long. I'm not expert enough to concur or disagree with this guy, but I thought it was worth passing it on.
https://www.youtube.com/watch?v=NGVRGsoOr6k
J.
https://www.youtube.com/watch?v=NGVRGsoOr6k
J.