A couple of things to consider:

If you're facing a grizzly or a big brown, you might consider using the 45 on yourself instead, as it will only affect the big bruin by enraging it further. In fact, I can't imagine any production pistol (short of an exotice big bore single shot) that would be an effective deterrent against big bruins in a confrontation. Average sized black bears are a different story. Many of them have been taken on a regular basis using 44 mag penetrating loads. I have a 300 grain stiffie that is devastating on moderate sized blackies at typical pistol ranges.

223s have more energy than a standard 44 mag load, but lack the momentum to effectively thump big game. They are well capable of taking deer sized game, but I would hesitate using them on big predators, as their performance characteristics do not fit the profile you would desire.

The comparison is similar to hitting them in the ribs with a sledgehammer thrown at them at about 60 mph (the 44 mag load) vs pushing a 5 foot long 8mm drill bit through them quickly, or slapping them in the ribs with a big wooden spatula. In order for a 223 to penetrate enough, it must be designed so it won't open up on impact much, if at all. If it opens up quickly, it won't make it to the vitals, and will only sting the beastie.

The name of the movie, btw, is "The Edge". A 44 mag is more like the big spear that the bear falls on at the end of the fight.

Speaking of cartridge selection in a handgun, if a stiff heavy 44 load (300 grain flat point at 1,330 fps in my case) won't do the job, I doubt anything else is gonna do any better. A handgun is just not a reliable tool in dealing with griz. <img src="/images/graemlins/shocked.gif" alt="" />