Have him read his manual. Lots of times there are suggested loads for the rifle in there.

Otherwise I would have him look at some powerbelts with about 80 grains of powder. Also some Shockwaves might shoot well also. It is all guessing on my part though to be honest.

I have never (well almost bought one) owned a .45 caliber fast twist rifle. When I was considering them, there was lots of rummors of them being hard to tune in with a good projectile. Keep us posted when your friend gets a load worked up. It would be interesting.