Think .44-40.
Look at reliable data from the powder or bullet companies, I start with Hodgdon and Alliant.
The 3 powders you have are for full power loads, trying to reduce them will result in erratic pressures. Find Universal, Power Pistol, Unique or any of a dozen other medium burn rate powders. People all have their favorites, but there are many useful ones.
Then pick up some plated or coated bullets of about 200 grains, load them to 800 - 1000 fps. You can use the XTPs, but it seems like a waste and by slowing down heavy bullets you can run out of sight adjustment.
Mid-range loads of this sort will cause much less wear and tear on you pistol and on you. They will accomplish 99% of everything you need to do and allow you to practice for the times you use the full power XTPs.
