Quote Originally Posted by rwilson452 View Post
As always when starting a new load, start with a lighter charge and work up.
Agreed - most manufacturers suggest 10% below the max charge as a new starting point or the minimum charge listed, whichever is less.

NEVER, NEVER, NEVER MIX POWDERS!!!

Alliant has a great explanation about the characteristics of powders in the front of their manual which is available upon request.