Loading for an AR (or similar) is different from loading for a bolt action. If you are using only a bolt action, it is FAR better to neck size only. That way you always have zero headspace (and perfect chamber fit), and cases will literally last forever. I have around 100 .223 cases (mixed headstamps) I have reloaded dozens of times. For about any semiautomatic rifle, you will probably need to full-length resize fired cases, and you won't get long case life.