I am planning on buying a new press in the near future (Dillon 550 or 650) and am wondering what the advantage, if any, of one over the other. How hard is it to change calibers on these presses. I looked at the instruction manuals online and I hope it is not as difficult as it seemed from looking at the manuals. I have never seen either press other than pics and am thinking it would have been easier to understand had I been looking at one of those presses. Wanna kill these ads? We can help!