Magnum Wheel Man,
You have a lot of chamberings, but didn't talk about the one-session loading volume of any of them. That seems to me to be the deciding factor for progressive over sequential (turret) or batch (single-stage) loading. I have a Dillon Square Deal that's dedicated to .45 Auto because that's what I shoot most. The dies on it never change. I have a 550B mainly for other handgun rounds I load less often, but still do at least five hundred of at a sitting. The 550 will also function as a single-stage press, since the indexing is manual. But switching out the priming system to change primer size constitutes enough extra bother that it pretty much just gets used for cases that employ small pistol primers. I load few enough .44 Mag and .44 Special rounds currently that I just batch them on another press.
All my match rifle loads get done on my Forster Co-ax press. I used to run some .223 on the Dillon, but between pre-decapping and cleaning before sizing, and trimming and cleaning off case lube after sizing, seating and setting primer depth to gas gun specs, there are simply enough interruptions to the flow of my process that I don't find the 550B saves me a lot of time with them. It can charge and seat, saving me one handle stroke or two if I am crimping for some reason (seldom), but that's about it.
Of the several single-stage presses I've accumulated over the years, the Co-ax is my clear favorite. Dies pop straight in and out same as putting a case in shell holder and just as fast. It lets dies and cases self-align to produce very straight (coaxial; hence the name) ammunition. I don't need to change shell holders for anything I do on it, since the small plates cover the head diameters Edward5759 mentioned. I would have to change to its larger plates for .45-70, so my Lee Classic Cast single-stage press gets to do those.
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