As a reloading instructor I am going to challenge that, depends on how you define hard. Many students struggle with it. Shotgun shells are much easier, but the nuances of metallic cartridge reloading take years to learn. To use a analogy, that is like saying rebuilding motors is not hard. While I am in fact capable of doing it I know for a fact I do not do it well. While the motor may actually run (eventually) my skill set left an enormous amount of potential and reliability on the bench. Reloading metallic cartridges is much the same way, yes you can make it go bang but how much potential did you leave behind?