There was an article on this...

by DiamondD, Monday, March 21, 2016, 23:22 (3172 days ago) @ Bryan Pettet

Thanks Bryan I hadn't seen that article yet. There is a lot of information out there, I just don't know which of it is based on FACT! Some people and even some loading manuals swear that the .17 Remington is based off the .223 case and some say it is made with a .222 case. Everyone pretty much agrees though that the .17 Remington and the .17-223 are ballistically almost identical. I have heard that running once fired .223 brass into a .223 FL sizing die with the guts removed and then through the .17-223 FL die is all you need to do to form cases. I've also heard to run it into the seating die and then the FL size die. I reckon I will be able to report back first hand here in a week or two. Just would really like to talk to someone who has actually formed cases before I jump into buying dies I may not need.

Should be a fun project.