There is no reporting on sales of magazines, you could buy from anyone in the world ... literally. It’s a fools errant to try and trace magazines, or limit the capacity.
Reloading is not that difficult, if practiced. This person knew what they were doing, and likely practiced, simple as that. Move, shoot, reload, it’s a drill practiced if you are serious about defense. It is not that hard a drill to master or become proficient at.
Yep. Not your average college student upset with a girlfriend.