B2,
Keep the brass at around .448 rather then the .451 though I'm sure both would work. The core seat die is really needed with the 45s and it is right around .449ish.
Using my universal die with the expanding mandrels will really show you if you get some brass that is not fully annealed.
Have you figured out how to flatten the base/head of the case yet?
Let me know if you need some 45 cal dies. I'm also working on the 22 cals for you as well.
Good shooting
BT