I have reloaded the 140 AMAX and use H4350 like the factory load. I have gone up to 43grns and got 2870fps from it. The factory load of 41.5grns is a good place to start.
I use the standard Hornady FL dies and just added the micrometer stem to the seater. Loads great ammo. Redding is also coming out with dies for the Creedmoor also.
Bullets and brass you can get from the usual suspects but Creedmoor Sports always seems to have the brass when others are out. Also the Gun Stop usually has some too. I like the 140 AMAX. Accurate and priced right.