It's always nice to not have to change primer feed sizes. I have 2 550s and 2 750s and I don't change. I may sell the L size 750 as I haven't loaded any thing on it. Yet. I bought a Dillon 550B at a garage sale last weekend..Looks new...but no primer feed parts at all. No powder measure either...100 bucks. I also bought another medium size tote with reloader parts and stuff just because...there was a SDB tool head and 2 SDB Primer set ups marked L and S. 30 bucks and a whole lot of other stuff in the tote. a complete set of FA bullet seating dies...or whatever it is. When I got home in the bottom of the tote was a complete new 550 Powder measure...and a whole bunch of Pachmayr handgun grips...like 15 of 'em. Still no primer feed for the 550B...but I figured on selling the 2 SDB feeds to kinda get the stuff I need for the 550. Anybody need a whole buncha rubber grips...or??...Heck I don't even need the 550. I spent way too much at that garage sale...but got a SA Hellcat for my daughter...but she's paying for it...Checks in the mail! Maybe