The following is meant for the nay-sayers of the .41 Magnum. I will give my oppinion to jphelps4 at the conclusion.
The only incidents that I know of, where Polar Bears were taken with the .357 Magnum, intentionally, were in a totally different era and the handgunner was backed up by a professional guide and the bullet did not come from a 4" barrel. The original load for the .357 magnum was a 158 gr. SWC at around 1550 FPS from a 6" barrel (843 ft/lbs of energy) and you ain't gonna find it today at wally world in a whitebox. If you get 1250 FPS (548 ft/lbs) from a 6" barrel today with any factory ammo, consider yourself lucky and you will need a chronograph to find out. Current ammo is held to 35,000 PSI. Yesterdays was loaded to nearly 50,000 PSI. If you have a chronograph, it is about a 95% sure bet that you are a handloader anyway and everything changes if you are. So go ahead and get that .41 Magnum. Ammo can be found except maybe by the hopelessly lazy. Handloading will be where you need to go in time and the truly serious handgunners that I know for the most part, are also handloaders.
First, lets make sure we are talking about black bear and not Griz. There's several hundred pounds of difference and all of them are best avoided. Black Bear will fall to the .41 or .44 magnum about as quick from one as the other. Shooting a Griz with a handgun better be a deliberate idea with a high powered rifle backing you up. The suggestion of a small carbine is a better idea than a handgun in Grizzly country, the carbine would be better in .444 Marlin, .45-70 Springfield or .450 Marlin. Sure you can take a Black Bear with a heavy handload in .357 Magnum and it's been done... Usually from a tree stand!
For excitement that may not be as lethal, go out to your local bar or wherever and take a punch at a 400 lb. man standing about 6'-6"if you can find one and remember, he doesn't have claws that will rip through your flesh and right through your rib cage. He most likely won't have canines about 2" long and power in his jaws to bite through bone. He will also not be nearly as quick as a large male Black Bear.
Why is the .41 Magnum not as popular as it should be. Well, bad advice ranks right up there! .019" more diameter surely makes the .44 more powerful doesn't it? Lets find out! When I started handloading over 20 years ago this myth was addressed and I don't think it has changed vastly since then in common bullet weights and loads for both. Factory 240 gr. .44 Magnum more often than not was actually coming out of the barrel at 1250 FPS and not the factory rated velocity, that's 833 ft/lbs of energy. Less than that of the .357 Magnum fired into a Polar Bear by Daniel B. Wesson. The 210 gr. .41 magnum would yield usually slightly better than 1350, but we'll use 1350. That's 850 ft/Lbs and considering that the 210 gr. .41 Magnum bullet has a higher sectional density than a 240 in .44 Magnum, with equal energy the .41 will penetrate deeper than the .44. Of course you can handload either of these loads with the right powder to over 1500 FPS, but not from a 4" revolver. If you tell me you can, provide the data from a 4" Barrel.
The advice given about heavy recoil in 4" barrelled revolvers was real world advice, not internet machismo from Rambotito! There are always a good number of Smith Mountain Revolvers on the used market immediately following a release of new guns. It would appear some don't know what Mountain Gun actually means. It has nothing to do with plinking at the gun range, unless you had the sense to load it with specials. The least likely of the Mountain Guns to be bought and sold the same week is probably the .45 LC, because it is not designed for pressure above the standard level, which happens to be 14,000 PSI and S&W is not going to tell you that it's okay to load +P. If you want a Magnum .45 LC at around 30,000 CUP, better think Ruger Redhawk or Blackhawk.
From a 4" revolver, when you reach the tolerable level of recoil and I don't mean by firing one cylinder. Lets say 50 rounds. My personal minimum. At the same level of perceived recoil the .41 will be delivering a higher level of kinetic energy and better penetration than the .44 because of the physical aspects of recoil in guns of identical weight. Higher sectional density because of it's length to weight ratio. The other factors are velocity, bullet weight and to a lesser extent, the powder charge. All being greater in the .44 except for velocity that is the major factor in kinetic energy and uses the square of it's velocity along with bullet weight in the ballistic kinetic energy formula V2 x BW in grs./450436= KE in Ft/lbs. This works the same way in all cases where you are comparing the two calibers in identical guns including the Ruger Redhawk, if you can find one used in .41 Magnum. The limiting factor for the .41 Magnum will be design pressure of the cartridge. You can load both to the same pressure and when you do, the .44 will be superior, but at that level, more than likely, you ain't gonna shoot 50 of them. And, if you don't get adequate practice, better go with the carbine. You can get 210 gr. bullets for the .44, but they will have to be loaded to a higher velocity and greater kinetic energy to obtain the same depth of penetration because of the lower sectional density of the .44 mag.
Wrong ppinions have led almost to a demise of the .41, but not for me. If you know your gonna pack a 4" revolver, might as well pack some logic with it. The .41 Magnum will kill a Black Bear just as dead as a .44, or any other animal within sound logical reasoning for that matter, of course it goes without saying that it depends on the man behind the trigger!
jphelps4, my recommendation to you will be a little different than what you might want to hear, but I promise you it is based on experience and a thorough understanding of ballistics. The only available 4" revolver in .41 magnum that I know of is the current blue steel Mountain Gun and it will serve you well, but with full power loads, it will kick like a mule. Handloading is the solution or getting someone to load you 210 gr. bullets at no more than 1200 FPS and preferably less, would give you a manageable gun to practice with and when on the trail, load it up with full power loads and block that mule from your mind. Easier said than done.
Ruger has a limited run of the Stainless Bisley Super Blackhawk in .41 magnum with a 5.5" barrel and if it were me, I would buy one before they're gone, even though I prefer a DA revolver over an SA for this purpose. If you can find an older 4" model 57 Smith, God Bless you, they're scarcer than hen's teeth. If you choose a SA Ruger, the Blackhawk is still listed in the catalogue, you should develop as much skill as you can in rapidly cocking that single action hammer and firing. A Standard 4 5/8" Blackhawk in .41 is a valued field gun with experienced big bore hands in the field. The 6.5" is not a bad option, just not as handy as the 4 5/8" if you can, have a steel Bisley gripframe mounted on either and they will be imminently more shootable. Why Ruger can't keep the standard Bisley in production chambered in .41 Magnum is beyond me, but they will bring out a Super Redhawk in .480 or .454 Casull with a 2.5" barrel. Idiotic~! Unless you do live in Alaska and even then, I'm not so sure. The last two options are also slightly different from your goal, but you may like the last one. Taurus, as far as I know still makes the Raging Bull in .41 magnum with a 6" barrel. 1" of which is occupied by the ported area. It is a heavy revover, but a very solid one. I don't always endorse Taurus products, but in this case I would. Cylinder is locked in front and back and I believe on the ejector rod like the old S&W Triple lock which was the forerunner of the N-Frame magnums.
Last and hopefully best, call Dan Wesson if you are as serious as I am about someone possibly going to deadly combat with a Bear! They make one of the finest revolvers known to man, but I don't know if they offer the .41 Magnum with a 4" barrel. My guess is that they do and it would be a little heavier than a Mountain Gun, but not too heavy to pack on the trail with Bears, Danger Close. One final thought; Ruger Redhawk, Blackhawk, N-Frame Smith, Dan Wesson, the true .41 Magnum Fans and not the closet variety that tell you that they have one, but you should buy a .44, and if the shoe fits....The .41 Magnum is a more accurate round than the .44 and the serious .41 men know it and won't be without one for that reason. Not because it has Less recoil. Put them in aransom rest and I will stack my best handload in with my .41 Magnum against someone elses .44 Magnum. I have honestly never fired a .41 that wasn't a tackdriver. I have fired .44s that were also tackdrivers and I have fired .44s that weren't.
BillCA, thanks for the current data on factory ammo. Like I said, I haven't bought factory in a number of years and I failed to mention the importance of selecting a good bullet for the task and if a handloader is available, the Sierra 22o gr. Tournament Master is a great choice. Even though it was designed for silhouette, it will expand on large game. Not a lot but with the penetration it will also provide, it will get the job done effectively!