I use a cutoff wheel on a 4.5" angle grinder (mounted in a bench vise) to cut the 223 cases off at the shoulder/body junction. Then deburr, size in the 300 Blk FL die, trim to length, and deburr/chamfer. That's a bunch of steps, but I haven't really bothered to streamline my process for it yet.
I don't normally anneal, but some people do.
There are easier methods if you want to invest a little in equipment. There are some good jigs available to work with a small Harbor Freight chop saw; those are supposed to work pretty well and I've heard you can skip the initial deburr step. My abrasive cutoff blade leaves too much burr, so if I don't deburr before sizing that stuff scrapes up the case necks.
Another method that looks good (but a lot more expensive) is a Dillon or aftermarket trimmer mounted in a Dillon trim die; that setup can size then trim (while the case is up in the die) in one step. Even the cheaper aftermarket trimmers for this are ~$200 though and the Dillon trim dies are pricey as well.
