My RCBS 2 die set came with 2 expander balls.
Something to consider is a custom sizing die, as while these cartridges headspace on the rim, the shoulder dimensions of these chambers varies greatly, and if you keep setting the shoulder back, you will get case failures at the shoulder junction.
CH Tool and Die will make you a custom sizing die to fit your chamber for not a whole lot of money, and your brass will last indefinitely.