I was watching a YouTube about changing the return spring and firing pin spring on a G21 to convert it to use with 45 Super. Why would they change the firing pin spring? I guess they made it stiffer, but not sure? I'm asking because I'm in the process of converting my Gen 4 21 to use 45 Super. I will only be doing this for camping purposes, so 99% of my use will be with standard loads or +P occasionally. Thanks... Wanna kill these ads? We can help!