Angus: please understand that you CAN break one with stupid reloading, m'kay?
The good news is that if you're careful and start with good standard 357Magnum recipes, you have some "breathing room" for newbie mistakes.
I would tend to recommend you NOT load "super hot" 357 made for this large frame and cylinder until you've gained considerable experience.
The thing is, adding powder in even very small amounts can give you enormous spikes in pressure. You can get to a situation where adding 5% more powder gives you a 50% or more increase in peak pressure - and it's peak pressure that can kill the gun.
What this means is, "exploring the edge" of a gun's performance envelope is best done with great care backed by experience.
The good news is, as you grow as a handloader you'll be able to explore more of this gun's capabilities, which are considerable
. It's a fantastic gun to learn handloading with
.
I have a NewVaq in 357. It's cylinder is still beefier than a GP100 which is by no means a weak gun. Your gun's cylinder will dwarf mine in turn
.