I have seen quite a few bears taken with a 30/30, it is probably the most common cartridge after the 30/06 around here where bears are shot over bait. I've registered bears over 400# that were shot with a 30/30 and it seemed to do the job. I saw very few taken with slugs but those I did see were usually taken with the Brenneke style slugs. I have only seen a handful of bears taken with sabots, of those I haven't been overly impressed. By reports, they did not seem to be as effective as the normal Fosters and much less than the Brenekke. There may be some today that are better but I still wouldn't trust them as they have been mainly designed and marketed for deer and for considering the range used, the accuracy improvements are not needed. I have heard stories and helped track a few bears that were not so successfully taken with both rounds, poor shot placement was invariably the reason for the poor performance. With either, do not shoot for the shoulder, try to put the bullet just behind that area into the lungs, just like you were using archery equipment. This will easily reach the vitals and will most likely exit helping to leave a blood trail to follow. Hits to the guts need no explanation but shooting the shoulders of larger bears is not a great idea as these bones are very thick, dense, and angles which regularly defeat more powerful rifle rounds. Even if the slug or bullet get through the shoulder, the odds of an exit hole are greatly diminished. This is extremely important if over bait and you are shooting down; the entrance hole will be high on the animal and what little blood may come out will be quickly sopped up by the fur. An exit hole, being lower and hopefully larger, will be better able to leave a blood trail for follow up. For ammo, I would use either one of the standard 170 gr bullets like a Core-Lokt (my favorite) or Federal Fusion or splurge and buy some Federal Premium Vital Shock with the Partition bullets. Thee are some of the tougher bullets out there and should be able to handle the larger, more muscular bear. I would hold off with the Hornady LeveRevolution as the higher velocity might decrease the close penetration due to greater expansion if hunting over bait. If it is a spot and stalk typehunt, I might go with them. Best of luck.