It’s been pointed out in comments to the post below about holding your revolver with a thumbs forward grip that a guy blew his thumb off using a similar grip and a .460 S&W X-Frame revolver. In the interest of clarity, the thumbs forward grip is safe to use on high powered magnum revolvers if you use it correctly. The guy that blew his thumb off is a classic case of “doing it wrong”. Here’s a picture of how he was holding his gun when the “accident” happened: see how the support hand is holding the frame of the revolver and not the stocks? That’s not good for a couple of reasons. While it allows you to support the absurd weight of the X-frame better, “tea cupping” under the frame like that obviously places the thumb of your support hand at risk and also reduces your ability to absorb recoil with the revolver.
In that picture, the hands are broken – not in the sense of broken bones, but rather there isn’t enough contact between the firing hand and the support hand to create a strong grip on the revolver. Even if you don’t injure your support hand shooting like that, the recoil will most likely torque the revolver clean out of your support hand anyway. The danger in shooting the big X-frame revolvers is the temptation to cheat on your grip due to the weight – they’re big, heavy guns and they’re built that way for a reason. Personally, I don’t particularly see the appeal in those guns. If I want a magnum revolver, it will say “.44” or “.41” on the side, and if I want a .599 Heffalump Magnum, I’ll get a T/C Encore or something. Not to disparage the super magnum revolvers, they’re just not my cup of tea.