This is an old thread, and probably
@sgt_zim has already made his decision, but in the event he hasn't... well... here it goes..
Everyone will tell you that a big magnum revolver is leaps and bounds above anything else in terms of stopping large carnivores... They may be right. I have never had to do it and hopefully, given proper shooting with my hunting rifle, will never have to do it. That said, I go black bear hunting each and every year and every year I carry my tried and true Springfield XD .45 super:
Its got some wear and tear but it goes into the chest holster and carries nicely. I can very quickly dump 4-5 rounds into an 8" target from 10-12 yards from un-holstering to last round fired in about 3 seconds or less. I have owned .44 magnums and .357 magnums but I could never achieve the speed and hits with a magnum revolver that I could with this one. With a solid grip, it hardly flips up at all and each round carries over 650 ft-lbs (currently still fairly low pressure. I could push more now that I have a ported barrel but I don't think it is necessary). The difference on target between this gun and a 10mm is pretty much indistinguishable (sold my 10 to buy this). I reload and my .45 super drops brass 8ft to my right. The 10mm would throw the brass almost as hard as the bullet.
There are people that will say the 10mm is more far more potent than a .45 super and from a numbers standpoint, not vastly different but they are probably right. 700-800 ft-lbs with top loads in a 10mm vs 650-750 with a .45 super. I am not going to argue levels of anemia here. They are both woefully under-powered compared to the rifle you are likely carrying. In the event that it is all you have, well if Phil Shoemaker killed a coastal brown bear in defense of his fishing clients with a compact 9mm... With proper placement, these will do the job just as well.
Anyway... I say all that to say... from a holistic bear gun point-of-view (the package,carry-ability, shoot-ability, speed, and power compromises) I think the 10mm and .45 super are just as effective as the big bore revolvers. Maybe not on a single-round basis (magnum will definitely be more effective if you can only manage one hit), but I would bet basing it on an "encounter by encounter" basis the successful defense ended the same. Wounded carnivore running off/Dead right there, and hiker/fisherman/hunter trying to get their heart rate down to a level where they can once again communicate.
The reason my vote also goes to .45 super is a lot of guys already have a .45ACP that can handle a limited number of .45 super loads. Any modern 1911, SIG, H&K, Springfield or Glock (with a fully supported barrel mod) can easily handle a few dozen rounds a year.
All that rambling is to say... I wouldn't limit myself to a big bore revolver if all you are looking for is a practical bear gun that will fit in your chest holster to be with you at all times. But... I am not the keeper of your wallet and if a .454 casull strikes your fancy.. HAVE AT IT!! The fireball will stun them if the bullet doesn't. I have never fired one but I hear it is a little like catching a baseball bat in the webbing of your shooting hand.
However if plain old black speed loaders will do, then the HKS 25-5 fits the Ruger Super Redhawk .454 Casull quite nicely.
