I have never heard of a book that says not to reload 357mag. I have been doing so for many years. It is also one of the easiest to load for, every bullet manufacture has loads developed for this round. For powders I have found that W-296 works great for me. The only reason I can think of for not reloading is that many gunshops that reload bulk ammo do reload 357mag and you can buy a box of 50 for $4 around here. Go ahead and reload, it is fun, easy, safe when instructions are followed, and can give you something related to shooting to do when the weather doesn't cooperate.