Shadow9mm,
What you say about lower capacity is true for 7.62 NATO, and to a smaller degree of 30-06 with modern cases (there used to be Peters 30-06 cases that were 215 grains, where Lake City run around 195 grains) currently produced. But all the Lake City 5.56 NATO I have actually has a little more capacity than the common commercial brass. There's a good list of case weights and capacities on 6mmBR.com if you click on their 223 info. The main thing that distinguishes Lake City from non-military brass is the heads are harder.
When you look at CIP Max pressure for 223 Remington, it is the same as SS109, which is 4300 bar (62,366), so if you have bought European 223 that wasn't specially loaded for the US market, your gun has worked at that pressure, according to their instrumentation method. Where you might hesitate to go is to the higher pressures now being loaded by the military for M855A1 and Mk.263 mod.1 for shorter barrels. They have higher pressures than the original M855 and Mk. 263 mod. 0. The higher pressures come from using a faster powder to cut down on muzzle flash in shorter barrels without giving up MV. The military has reported accelerated throat and barrel wear.
So, the recipes should be pretty much interchangeable if they have been established in the same measuring system or in different systems both calibrated to the same lot of reference loads.