Please do not put words into my mouth I did not say anything about using a cast 223 for bear.
I use a 60 grain Nosler Partition do very well as does the TSX. The .223 is used a lot in and been very Successful in many parts of Alaska for hunting Bou, moose, bears.
I have a buddy who is a native and in Alaska and he uses a 243 to hunt everything and he takes brown bears with his 243 every year.