Just some friendly advice, and I do mean that -- the kind of advice I would love to have gotten 20-25 year ago when I finally ventured in to other cartridges at the load bench beyond simply the .38 Special, .45 Auto and .30 Carbine I was loading.
This is a mistake, it's a poor habit to get in to and if you actually load lots and lots of all of these, it's almost a false economy.

When we look at the four components that make up a loaded round... we could argue about the cost/price of the brass we re-use, but ultimately... especially in most handgun rounds, the powder is the least expensive of the components.

When you get in to the habit of "settling" for a powder simply because it works in multiple places and you think you are saving money... all you really end up with are loads that end up being a compromise.

If you instead get the powder that is best for the job, you'll make the best loads and you have a side benefit of having lots of powder options when a new cartridge shows up at your bench.

This realization took me years and years to discover and embrace personally. And I have zero regrets.

When you look at the pressure the .460 Rowland aims for, it should be obvious that you are going to build not only better loads with a slower burning powder, you are also making SAFER loads with a more predictable top end.

You are talking four different cartridges with one powder. Is it possible? Yes, sure. And if you are willing to have not a single one of them doing it's best, it isn't even difficult. But it's a false economy and every load you make is just "settling for something that works good enough."

I bet ten years from now, you'll have 20 different powders in your cache, and I'm just talking pistol powders. I think your best bet is to pick powders that load those cartridges perfectly.

And for the .44 Magnum, make your brother buy the Alliant 2400 or Hodgdon H-110 that it really enjoys if he wants the full-nuts .44 Magnum experience.