I did a lot of research on this when I first started really getting into it and most people say it is totally safe to store them fully loaded. One guy pointed out magazines from world war 2 being found and firing perfectly. The ammo as well, as long as it's stored properly. These magazines for the shield I honestly have to keep fully loaded to loosen the spring because some come very tight. Only time I hear it's recommended to keep one less is on the long extended mags. Some use the same exact spring as the regular magazines which means less power.