I also have a RCBS powder measure. Can I use this on a Dillon 550B too?
I sometimes use an RCBS measure on my 1050, so you should be able to do the same on a 550B (perhaps someone can confirm that there is sufficient space in the relevant station). You would need the RCBS Case Activated Linkage kit
, which fits the Uniflow-based measures. Apparently expander options are available that work with the case activated linkage kit, like this one