The 550B is easier to swap out rounds than the 650. If one is into high volume loading, enough to dedicate one press to a single round, the 650 makes sense.
I do most of my handgun loading with a 550B and have around 10 tool heads set up for the different rounds. I don't use my Dillon for rifle loading.
When a Dillon is being used for rifle rounds, I would think the use of a ball powder for easy and accurate powder charges would be desirable. I'd try to find a load using one of the Ramshot powders if possible. Nothing feeds better thru a powder measure, IMHO.
DF
