I am looking into possibly adding another progressive to my bench and keep coming back to the same thing. that 550b would be perfect for MY situation. But I would be looking for something in between my single stage presses and my XL650's. If I only had a single stage and was looking into buying just one press with a powder check die/station, My choice would be either the Dillon XL650 or the Hornady Lock/Load AP. But there are other factors...the main one for me would be this:
1. How many different calibers?
If it is just one caliber or calibers with the same size primer, then go with the XL650. Hard to beat it.
If your will need to change calibers and primers, maybe the Hornady might be the way to go since I have heard that changing calibers/primers is very quick compared to the XL650.
They are both very exellent machines. I prefer the Dillons but for my own reasons.
* * but only if you purchase the case feeders for either choice, otherwise, the Dillon 550b all the way. This little workhorse is really hard to beat. Here's why:
I have two XL650's both equiped with Powder check systems/dies in station 3 and lights mounted on the press to illuminate the shell plate but for what it is worth, I STILL LOOK INTO EVERY CASE BEFORE I SEAT THE BULLET. If something don't look right, I will pull that brass off of the press and inspect/check/verify all pertinant details. I know I could probably set records in terms of how many rounds per minute or how fast I could load 100 rounds but my usual time of 15 minutes per 100 being very careful is fast enough.
That said, the 550b looks even better.
Cheers, Mate