Where are you finding loaded 123 gn A-Max? I'd love to get my hands on some. Although, to be fair, the Hornady Black 123 gn ELD-M is a smoking deal (assuming it shoots) at around $15 a box.
I ordered a case of the cheapo WPA stuff to do a bargain brand shoot out between the 5.56 and 6.5 - because the 6.5 is actually cheaper to shoot (and about even for the match ammo).
I am waiting on "good" ammo at the moment as well as mags...you can jam an empty 6.8 SPC mag (not sure on 5.56) in the rifle and enjoy it as a single shot - I did that to test function. Everything is TIGHT, but it runs just fine. I just mounted a Viper PST 5-25x50...which looks absolutely comical...but...if it's worth doing, it's worth over doing? Honestly, the AR-15 is light and handy enough that it actually handles pretty decently offhand when dialed down to 5x...it just looks absolutely silly.
I'm still waiting on the 5.56 kit...I am thinking about selling my 7mm Rem Mag just to poach the optic (a Viper PST Gen I in 4-16x50...so, still comical, just a little less so), heh. I intend for this to be me GOTO 5.56 and will convert my existing DDM4V1 to 6.8 SPC (probably with a LaRue handguard...also on sale for $209 at the moment...).