I am planning on Black Bear hunting in Colorado this year and was wondering what would be a good load to use in my .458 lott. I will be hunting mostly in thick timber so shots will be close range. I was thinking about just using factory hornady 500 softs since they are what Ruger used to sight in my open sights. Would these bullets be too tough to expand or do damage on black bear or would I be better off with some lighter and faster 350 grn or 400 grn bullets?

Since the range will be short, I'd go with a 400-405 at about 2200.

I wouldn't worry about, there is no such thing as bullet failure on bears with the 458 Lott...

The 350 HORNADY RN at any velocity fromm 1800 fps to 2350 fps will do an excellent job.
This bullet also fed perefectly in the 2 458 Win rifles I had.

The only problem I've had with short range is,when I get there the one shot turns out to be long range and visa versa..What I'm saying is,I'd go in barking 82 grains of h4198 behind a speer 350..Blast him at 50,blast him at 250

Ak

I wouldn't worry about it, stick with your original plan. Just go ahead and use the 500 gr softpoint factory load you have on hand. Experiment with other stuff after your hunt. The soft would probably expand some but you'll stand the very good chance that it'll just punch all the way through the bear anyway.