Brent you have a learning curve to go through if you are taking up the Martini. Start here.

Internet Sites for Martinis, Related Material and Subjects

Use the CBC Brass. Forget turned brass, that is for heroric measures only. Read this next: Word of caution about balloon head cases

The big bottle neck does not load like a big straight wall case. No compression. If you load enough powder in a CBC case to get compression you will have an over load.

The standard load for a 577/450 Martini is 85 grs of either FFG or Fg. I have good luck with FG Swiss.

85 grains of FG wil not reach the bottom of the neck in a CBC case. The CBC case is balloon head so it has a greater capacity than a solid head case.

Oh, and you do know the Martini doesn't use .458 diameter bullets don"t you?