The 10mm is a joke if you are talking about big bears, and your life is on the line. The 10mm max's out in power at 728 ft. lbs. (Buffalo Bore and Grizzly) and 749 (Underwood). This is quite low in the revolver world. For instance, the .357 max's out at 907 ft. lbs, the .41 Mag at 1,074 (Buffalo Bore0, the .44 Mag at 1,544 (Buffalo Bore), and the .45 LC at 1,344 (Buffalo Bore) (and at this .45LC power level, you need to have a Ruger or BFR). All of these have substantially more power than the 10mm. So, if your life depends on it, do you really think that the weakest of all of these is the best? And if you are thinking that having a much bigger magazine makes up for the power difference, when you are being attack by a big bear charging at 35-40 MPH, you will have only a few seconds to fire, and maybe that would come to only 3-5 shots at most! Any for you loyal pistol owners out there, you can shoot a revolver just as fast as a semi-auto pistol, especially double action revolvers. With single action revolvers, like with the old Western style guns, you can fan these to get rounds off very quickly as well, as you see in a lot of westerns.