1. .223/5.56 ammo is sparse right now. Like, REALLY sparse. So much so that I have three training courses I'm attending between August and October, and I'm concerned that I may not be able to get ammo for it without paying at least a $100/case premium for really high-end practice ammo. PMC X-Tac is their variant of AE223 and XM855. PMC is very dirty ammunition and it tends to be less accurate than other 55gr options. However, at 50yds and in, that's somewhat inconsequential. For general range use, it's not terrible.
2. You may have a high-end AK, but it's still an AK. AKs were designed to shoot steel case ammunition. I would not waste time trying to find brass ammo, and then pay the premium for it, when steel case ammo will be just as good in that weapon. Even Hornady uses steel cases for their 7.62x39 TAP ammunition, which should say enough about it. Just my $0.02.