Has anyone harvested bear with these, and if you did, how did the round do and what weight bear did you take? (These rounds are a joy to shoot.)

Blessings of the season.

I took a 550 lb Black Bear with the 350 grain Hornady Roundnose. It was however a handload at about 1900 fps From the 1895 Marlin. The shot went in the top of the head and was just under the hide between the front legs. I have taken the bigger bears with the 45-70 but only with hard cast LBT type bullets.

It's not quite exactly what you're asking about, but I took a 340# Bruin with a Winchester Supreme Partition Gold 300grn a few years back...It did pretty well. Granted, that's a bruin, I think I'd have been using a little more bullet for a brownie (especially costal's) or grizz.

Prior to handloading for my 45-70, I took a 240 lb blackie with my 1895 guide gun using Remington 350 gr factory ammo. Range was about 60 yds. The shot was placed slightly back from where I wanted it as the bear was on the move. Even though the shot was less than ideal, he only went about 50 yds. He was going downhill at the time and I think he probably rolled about 10 or 15 yds.
Even though these rounds are loaded to be used in older firearms, they appear to be suitable for deer/black bear.
The handloads I use now are juiced up somewhat from the factory ammo, but I am still using the 350 gr bullets.