The 400 grain Bearclaw at 2,400 is a fantastic buffalo load. When I had my .416 Hoffman built in 1988 Remington had not yet come out with their chambering, but they’re nearly identical case dimensions with the Remington being very slightly smaller.
I called Trophy Bonded Bullets to order some Bearclaw softs and Sledgehammer solids. Jack Carter answered the phone himself (for those not familiar, Jack was the founder/inventor of Trophy Bonded Bullets), took my order after a lengthy discussion about the .416 and his fondness for the Hoffman chambering. He gave me his pet load, which was 81.0 grains of Reloader 15, Federal 215 primer, topped with a 400 grain bullet. He told me “that load is a hell of a good buffalo killing load”. He was right, it absolutely was. I got 2,510 fps in my rifle and it performed splendidly on buffalo and everything else I shot with it. It shot fairly flat too, I killed a gemsbok at over 300 yards with that rifle, which is the farthest shot I ever tried with it.
Nowadays, I shoot a slightly milder load of 79.0 grains of Reloader 15, same primer and bullet. Velocity is 2,405 and it’s still an excellent buffalo killing load, but with less recoil. Federal lists this load for the Remington, but if you want a bit more velo you might try carefully working toward 80.0 grains and see what your Remington gives you as long as there aren’t pressure signs.
Bearclaws and Sledgehammers are very scarce these days. Federal shows none available. Glad I’ve got a decent stockpile of them.