DakotaDeer,
The standard SAAMI maximum average pressure (MAP) for the .223 is only 55,000 PSI, when many modern rounds have MAPs of 60-65,000 PSI. The so-called "pressure" signs used by many handloaders such as primer pockets expanding, difficult bolt lift, and ejector-hole marks on the case head usually don't show up until pressures are above 65,000 PSI, and with some brass well above 70,000 PSI. So there's at least 10,000 PSI and sometimes 20,000 to play with above standard .223 pressures.
Apparently the reason for the 55,000 PSI MAP is reliable performance in autoloaders, though 5.56 NATO ammo, as I recall, is loaded to over 60,000 PSI. And two cartridges on the same case-head have much higher MAPs, the .221 Fireball at 60,000 PSI and the .17 Remington at 63,000. I don't see why loading .223 ammo to 60,000+ PSI would be a problem, bu conditions such as temperature, whether ambient or a hot barrel, can change pressure considerably. Which is why it's probably not smart to really push the envelope, whether with the standard .223 or the AI version.
