Take one case from each brand of brass you have. Fill each with whatever powder you are using, and tap the case-head gently a couple of times on your bench. Weigh out each charge. Write this down, as to full-case capacity and brand.
Arbitrary numbers; I've not loaded for a .223: If case #1 holds 30.0 gr, and #2 holds 29.5 grains, I would consider a max load in #2 to be 0.5 grains less than for #1.
This way you will know which brass can use, say, a book max load without over-presure: The one which holds the most powder.
Until you get your own "pet loads" all worked out, start at least 5% under maximum and work up while watching for pressure signs such as flattening of the primer. There is no engraving in steel which says you absolutely must shoot maximum loads, in your general practice/plinking ammo, is there?
By and large, I have never had any difference in pressure signs or accuracy among the different brands of primer. I'll take luck over skill, any day. Some guns are picky, however, and a change in brand of primer can sometimes improve accuracy.
The marking on the case is typical. Don't worry about it. Firing a cartridge is a torture test of the case; they've been enduring it for over a century, now.
Hope all this BS helps, Art