I hates pulling ammo, especially cast, cause they often leave the check in the neck when using a kinetic puller.  But I do it enough that I wore out one puller!  I had some too heavily crimped 30-06 to take apart.  35gr RL15 ought to give you around 1900@31500 with your 220.  Though it really doesn't matter, you appear to be working opposite of what most folks do.  Most would use the slower powder with the heavier bullet.  There's nothing wrong with doing it the way you are though.  Experimenting is part of the fun.