dillon SDB only pistol calibers
550B not auto indexing... more of a chance of a double charge! Could greatly benifit from another die station
650 costly ,,,,,
All Dillon machines come with a powder measure that has a slide bar, flake powders and small ball powders will cause fits
Consider the Hornady LNL AP. Much cheeper to change calibers if you are loading more than one . The powder measure is much better than what dillon offers.
I am pretty sure (POSITIVE) the 550b is manual indexing. I have owned severalThe 550 is auto indexing and I have no idea what I'd do with another station