I've had good luck with a number of factory .375 loads, including Remington 300g Swift A-Frames and Federal high energy 300g Trophy bonded bear claws. Both my Son and Daughter shot Buffalo's with the Federal load, which completely scrambled the Buff's heart after breaking the shoulder and then exiting the other side.

One time I took Remington Core-lokt 270g loads when I only planned to use the .375 on plains game, and that worked very well on Sable, Hartebeest, Eland, etc.

I think Federal 300g Trophy bonded sledgehammers are the best factory solids, tho I haven't tried the latest steel jacketed Hornady's. I found the Hornady heavy bronze jacket solids would flatten at the base, but I'm sure the new steel jacket ones are a different story.