I use a FL die for my Rock River and have no issues getting reloads to chamber.
It may also depend on the brass you are using.
Had some once-fired Winchester brass for a 22-250 that would not resize back to where it was supposed to go. On Sinclair's advice, I switched back to Remington again because it is a bit softer.
You will probably only know in that particular rifle when you start to reload for it.
Talk with one of the guys at Sinclair and they will give you the straight dope on what to do.
They help out even if you haven't purchased from them.
http://www.sinclairintl.com/aspx/gen...ontact_us.aspx
http://www.predatormastersforums.com...Number=1870285
http://www.ar15.com/forums/t_6_42/33...e_dies___.html
http://www.ar15armory.com/forums/Sma...15-t34097.html
Here is a good page for loading the AR15:
http://www.6mmbr.com/223Rem.html
Allen