I guess it really doesn't matter as I'm doing a bolt rifle I guess.
it's not about the type of action, it's about the bullets you want to use. The old 223 Rem chamber is more suited to light varmint bullets, while the Wylde and 5.56 chambers accommodate heavier bullets. In my experience the Wylde chamber shoots the light varmint bullets very well too and can be loaded to a bit higher velocity because of the freebore.
For building my own barrel as you will, the choice for me would never be between a 223 Rem and 5.56 chamber, it'd be between 223 Rem and 223 Wylde, with my choice in most situations going to the Wylde. Your choice may differ.
Of course there are a number of other match chambers one could choose from as well.
