Marty
I really hesitate to offer this, but I have a great load using 350g Barnes bullets. In fact it's the only accurate load I've found with that particular bullet in my 458's.
The reason I hesitate to offer it is because it's a "duplex" load. That is, it's made with a mixture of LilGun and WW296. I know this sounds weird, but I did some experimenting a while back with a 44 Auto Mag (on a Contender) and it turned out to be a great combination in that caliber, both in the contender and the regular TDE Auto mag. Because it worked so well for the Auto Mag, I tried a similar (but scaled) load for the 458. The only bullet it offerred improvement to was the 350 Barnes.
I'll give you the load if you want, but it does require careful mixing as well as stuffing the case with filler to ensure the mixture does not change due to movement and/or temperature.
Let me know if you are interested.
Lee
PS. The 458 you put the brake on for me got a one shot kill of a 6-pointer this season. About 80 yards, quartering toward me, hit low in the left shoulder and he never took a step.