Both versions are ported, actually. That
off-color bit ahead of the front sight on the 500 is a three-port compensator. The
500 Hunter has a larger, multi-port compensator. Not that it really does much, especially on the 500. This thing generates so much recoil that a compensator is more or less there to make you feel better about shooting it.
Other manufacturers are hopping on the .500 Mag bus, namely Freedom Arms, Thompson/Center and Magnum Research (who imports/manufactures the Desert Eagle). I got to play around with the Freedom Arms .500 Mag at a local shop a few weeks ago. All I can say is that I can't think of any reason why anyone would want to spend the money on one of these things. They are so far outside of anything resembling practicality that it's just stupid. It's either an insecurity complex, the need to have the biggest, most powerful insert-name-of-object-here, some form of masochism or maybe all of the above that makes a person buy one of these. Whatever it is, I don't get it. The .500 Mag would be a lot more useful if someone would stuff it in a rifle, like say, Marlin. I'm hoping they do that soon. I might actually consider getting one in that case.
There have been a couple of single-action revolvers out there for a while that could likely compete for this "most powerful" title. Magnum Research makes a revolver chambered for the .450 Marlin cartridge, which was designed for the same rifle I'd like to see chambered for the .500 Mag (Marlin 1895). Gun Tests magazine tested this beast (8" barrel) and lists ballistic of Hornady's .450 Marlin load like this: 350 grain JFP @ 1610 fps = 2014 fpe. Not quite up to the .500 Mag ballistics, but you can handload the .450 Marlin to compete pretty easily.
John Linebaugh is a Wyoming gunsmith who has been making big bore revolvers for years. One of the cartridges he developed, the .500 Maximum, was most certainly the basis for the .500 Mag because the dimensional differences are very, very slight (within .025" of each other in both length and diameter). The hottest load I've seen listed for the .500 Maximum is a 450 grain JSP @ 1383 fps = 1911 fpe. And that's from a 6.5" barrel, 1.5" shorter than S&W's 500. (Here's a
Gary Reeder .500 Maximum). Given that the cases are almost identical in size, the .500 Maximum can likely do anything the .500 S&W Mag can with proper handloads, and it probably has been doing those things for years (about 12 of them). I guess it pays to have S&W's marketing and manufacturing capabilities.
I've had stats for the
S&W 500 on my site for quite a while if anyone is interested. I am thinking about changing the recoil modifiers to +4, however. It's a beast.