where are you finding these 400# bears? They are few and far between. Not that they don't exist,Just get very wary to reach that weight /age!
Either of the calibers you have will do the trick on baited bears,as the range is usually under 50 yards.If you just gotta have a new barrel and do handload, try a 309jdj or a 30-30 imp. I would not change MY 44 mag barrel ,it is too accurate and too much sentiments to alter it. jh :wink: