I have killed several black bear. I used a 300 mag in Montana and a 450/400 3 1/4" double rifle [spot and stalk] and I have used my 9,3x74R for 2 bears over bait. I took my last bear over bait, on Sept.6 with a 308 and 180 Woodleigh Soft Points, it worked fine....
However the outfitter stated I was the only one to have taken a bear with a 30cal without difficulty. He has had several take 30 cal hits and run off never to be found. He likes big bores for bear. His hunters have had excellent results with 45/70 and the 444 Marlin.
I think the best rifle for any animal over bait is a double rifle. Second best choice for black bear anyway would be a big bore lever rifle. A scope [@ a 1 to 6 power, even a 3x9 is too much for close in bait hunting IMHO] in QD mounts would be nice but I have taken 2 of my bears over bait with iron sights, but sometimes they come in right at dark, and a scope with a thick reticle or an illuminated reticle can make a difference whether you can shoot or not.
There is no substitute for a big bore when hunting big game up close.

I talked to a friend of mine in Whitehall, Michigan yesterday to find out how his bear hunt in upper peninsula went. He bagged a 210 Lb. male on the third day of his hunt. The bear took 4 hits from his 270 Win (factory ammo)the first three shots were from 85 yds. out. First one spinned the bear just behind the shoulder. The bear collapsed thrashing and bellering. The hind portion imobile he placed a second and third shot to the heart/lung area as he found out latter will field dressing. Bear's head on the ground now my buddy figures the bear is dead. My buddy is out of the tree stand and only 12 yards from the bear when the bear tries to get up and come after him. A fourth shot while in fear for his life kills the bear. I would have thought that the 270 would be enough for a black bear. Apparently not. Anyone have similar experience or comments.

Vaya con Dios, Danbro

Just read a post on another forum about a guy shooting a black bear 2 times through the vitals with a .300 RUM w/ 200 grain bullets @ 3000 fps and he still needed a finisher in the neck. Once an animal's adrenaline gets up, they can be tough to put down. I once saw a small whitetail doe that was driven take a .300 RUM 180gr Scirocco behind the shoulder and run 300 yards across a cornfield before falling in a fence row. There was nothing left of the heart & lungs. Not enough gun, or just a tough animal?

-Lou

A shot that wounds an animal gets their adrenaline flowing and it takes a bit longer for the animal to realize that it is dead from subsequent shots. The .270 is plenty fo black bear - the same thing would have happened with almost any caliber short of those used for African dangerous game.

NE 450 no 2,
I do not dispute that that is what your outfitter told you!!
Neither do I dispute that the .444 or 45/70 does a fine job on black bears.
I do dispute his claim that .30 cal is not a good black bear cal. There is no black bear or moose that will get away from an appropriate and well placed .30 cal in the heart/lung/spine area.Period!
I know that for a fact based upon first hand knowledge with a few dozen polar bears as well at least that number of black bears. Especially over bait it is easy to kill any bear. Your .308 Win with 180 grain Woodleighs was most certainly an excellent choice.
I have personally used the .308 Win with 165 bonded bearclaws and with 180 Nosler partitions with great success on Moose and black bears.
Nothing more painfull and un-necessary then shooting a heavy recoiler from a tree stand with your shoulder firmly braced against the tree. Black bears are not particular heavy boned animals and are easily put down with a well placed shot.
Probably the reason your outfitter recommends the .444 and the 45-70 is that it makes bigger holes and with wounded animals leaves a better blood trail. Specially the long bear fur often soaks up a lot of blood before it starts to leak. He is not concerned about gaping holes in your bear hide!Just with finding the animal after someone manages to hit it with less then a well placed shot. I imagine he does not recommend the .444 or the .45/70 because he truly believes the .30 cals lack the needed swift killing power.
However is there an excuse for a reasonable seasoned hunter to wound or miss a bear from a tree stand @ 50 or less yards, with his snout in the feeding trough and its mind fully occupied with the goodies? Giving the hunter all time and opportunity to make a good bullet placement?.
Should not be, but unfortunately it happens too often. I have seen Nimrods climb in tree stands with long barreled rifles in powerfull magnums equiped with large variables sighted in for 200 yards, landing up not being able to differentiate ass from nose, not being able to see the fine reticle against the black fur in an already dark forest in twilight, then overshooting the animal or plainly gutshooting them, since they thought they were shooting at the chest but oops it was the other end. Your outfitter has been probably through all this a number of times, seen it, been there, and therefore recommends the big bores to increase the blood trail and chance to find the animal after the not so infrequent botched shot. And.............where did I get all that first hand knowledge about a few dozen polar bears ranging between 250 and 1100 pounds? Before you get the wrong idea,I was a wildlife biologist in Canada and worked for 11 years mostly on polar bears and in between on black and Grizzly. During that time I witnessed my Inuit companions take dozens of polar bears on our sledding trips. The .308 with 180 grain bullets worked just fine. Every lung shot polar bear fell within 75 yards and died swiftly.