your buddy is severely misinformed. they don't get very big out this way either. my experience with black bear is pretty limited by my older brother took a small one(probably 150 LBs soaking wet) with a 223.
I took this 250LB guy with a 6.5 japanese carbine at a little over 100 yards.
to put that into persective, I shot this bear with a 140gr bullet traveling about 1900-2000 feet per second.
your weatherby pushes a 180gr bullet about 3200 feet per second.
last fall at 50 yards I shot my elk with my 300 weatherby which I loaded light to cut down on recoil. with a 180gr bullet it entered the skull then travelled all the way down the neck and exited through the front shoulder... about 2 and a half feet of heavy muscle and bone penetration. your 300 weatherby is more than sufficient for even the 600 pound Pennsylvania monster black bear.