In that case, I'm going suggest the Lee Classic Turret may make the most sense. It's slower to operate, but quicker to set up and involves much less investment since you already have the dies and shell holders. If you count the changeover and primer tube filling and intend to stop and changeover again after 500 rounds, the 550B will probably only be about twice as fast. It will let you get to 500 rounds pretty easily in one sitting of two hours. The Lee, if you leave it set up at the end of one evening, will let you finish a 500 round stockpile plus 50 rounds for the next range session on the following evening.
This guy is getting about a round every 10 seconds
off the turret press, not counting setup or supply replenishment. Figure three times longer with setup, supply replenishment, and working at a somewhat more careful, less frenetic pace for a couple of hours.