Had a 357 mag single shot rifle for many years. Daughter wanted to shoot and reload so I let her load 38 S&W cases with black powder and later with 4198 rifle powder. With a slow burning low pressure powder, it is simply impossible to overload or double load the cases. Just be able to set the bullet seater to proper length. She loaded and shot a few thousand rounds with that old gun. Then she discovered the guys who shoot because their dad brought them to the range.