I have a "pistol stock" called a One Shot that is designed for Glocks and complies with the law by not actually being attached to the gun. It's molded plastic that just fits very cleanly around the grip and your hand is what actually holds it in place. It works surprisingly well and it also works surprisingly well on a large variety of other guns including revolvers, CO2 revolvers anyway. I don't think it would work well at all on a .454 Casull. If someone were to copy the concept and make one specifically to fit a revolver grip I'm sure it would very well. It's the kind of thing that would ideally be 3d printed.
Despite how well it actually works, I can't really recommend buying one due to the ridiculously high price. They're about $70 and when you handle one you can tell it literally cost pennies to make. If you buy one you'll find yourself thinking, "Damn, this works really well!" and simultaneously, "I can't believe I spent $70 on 3 ounces of plastic."
