I'm sure there are others, but don't they have to 'contend' with these guys for the title?
That's their revolver, with ".45/70, .480 Ruger/.475 Linebaugh, .450 Marlin, .500 S&W, .50AE, .444 Marlin, .30/30 Winchester, .45 Long Colt/.410 (not for sale in CA), and the new .460 S&W Magnum - as well as .454 Casull, and the unique .22 Hornet."
They also make the Desert Eagle autoloader and a line of rifles that go up to 300 Win mag and .308. I know TC goes past the rifles, but does it go past the BFR? If so, it's not in a wheel gun, so you're talking one shot.
I understand about the sport of handgun hunting, but back when it was reasonable for me to consider hunting (before my eyesight failed) I would only have considered a handgun for backup and would have been hunting with something in either 30-06 or .308 (I would have been hunting with one of my uncles up in Wyoming and that's what they carried, mostly Army surplus rebuilt by them or friends on the res). But if I were with them the backup would have been for a bear that got inside our perimeter, so having more than one shot in a big bore pistol would have been high on my list of priorities. <g>
Now, if I were using a Barret one shot at a time is about right, so I wouldn't mind not going with one of the box fed versions of those mothers.
There's a video on YouTube showing some fairly large guy shooting a TC Encore. I don't remember the caliber. The pistol simply disappeared past the guy's head after he fired it.
I would have to guess that's the most powerful handgun in existance for a comparible size. I think there's a Fifty BMG handgun but it outweighs a rifle.