What everyone else here has said.
But, if your friend is game, I have a suggestion for how to give reloading a try. Have your friend make some 38 Special reloads, and shoot them in a 357 magnum. I haven't tried double charging a 38 special as a science experiment, nor will I. But I suspect that even if you screwed up badly somehow in charging the cases, a strongly built 357 would have extra strength built in and could mitigate the effects of an overcharge.
This was my thinking when I started reloading. I started by reading 2 or 3 reloading manuals. In fact your library probably has at least one so you or your friend could read up on it at no cost. I carefully made 6 38 special rounds, put them in my 357, and had at it. I was so nervous about blowing up my gun and my face that I was almost ducking down behind the gun.
Let me tell you, you won't often get a feeling of satisfaction like you will after doing this, and the gun shoots, and doesn't blow up after all. Wow, follow the instructions in the manual and with your equipment, and it DOES really work! My 38 special reloads shot just fine, if anything they were pretty weak, but that got me hooked. I then started working up to higher charges per the reloading manual, then started reloading 357 magnum, then 9mm, then... a couple of years later now I cast my own bullets, shoot nothing but my own reloads, and I don't know if I saved money but I'm so glad to have discovered a very satisfying hobby in its own right. And it has made me a much better shooter.
Have your friend read the manuals, and then if he's game buy a kit to set him up to load 38 special. That's one of the easiest to load for, they're very forgiving especially if you shoot them in a 357, and there are some real savings to be realized by shooting reloads over buying even 38 special.