I recently got 2 new .223 rifles, a WOA barreled SPR type AR15 (7" twist), and a Tikka T3X Varmint rifle (8" twist).  I've outfitted both rifles with quality optics, bipod, trigger, stock / chassis, etc.

I suspect both of these rifles should shoot well with quality ammo.  Problem is, I don't have any quality ammo (all my 223 is cheap steel cased crap I shoot through a different AR at an indoor range).  I have 2 boxes of Hornady Black 223 75gr bthp on hand.  I bought those 2 boxes last year to try out.  I can't seem to find any more of that ammo though.

I can find the PMC 77gr X-Tac in stock though.  Is that decent ammo?  How does it stack up to the Hornady Black?  I'm thinking about buying a couple of cases, since I'd have to order it.  Ammo selection in my city is pretty scarce...

I'd like ammo capable of MOA or better groups, if I do my part.  Local range is 325 yards.  I do sometimes shoot matches at 500 yards at another range.

I always shot 308 for "precision" before I got these rifles, so doing this with a 223 is new to me.

I've only shot three or four boxes, but it was all right around MOA in a couple of my AR's and XCR. The brass is good, too.

I've shot a case of this (PMC 77 gr) in 2 Daniel Defense 5.56 rifles, and one .223 Wylde Aero build. I was impressed with its accuracy, easily sub moa @100. However, it always shot about 1" low even at that distance, compared to other 75-77 gr rounds, like the Hornady Black 75's or the Magtech and Freedom 77's.  At longer distances, as you can imagine, the groups opened up, and the rounds landed even lower, comparitively.  I don't have a chrono to measure, but it seemed to be a little underpowered compared to the others, which made longer range shooting beyond 100 yrds less than satisfying. In my guns, the most consistently accurate .223 /5.56 75-77 gr factory ammo I've tested is the Hornady Black 75 gr, followed by the Magtech 77, and Freedom 77.  IMI 5.56 77 can also shoot sub moa, but it can sometimes shoot inconsistently and is a considerably hotter load than anything else, so needs a different zero.
When I shoot 500 yrd matches, I use the Hornady for the consistent accuracy. I can get around .5 MOA at 200 yrds consistently with my 20" Aero build ( last outing was .42 moa).
I've also used the Federal GMM 77, and found it to also be slightly underpowered and less consistently accurate in my barrels, but others swear by it - it's also the most expensive round @ $1/rd or more. As always, every barrel is different, so YRMV from mine.

Thanks for the info.  I think I'll keep looking for the Hornady Black 223 75gr ammo.  Seems hard to find at the moment.  Gives me an opportunity to work on some load development.

They usually stock that stuff at rural king.

I'd expect good results. PMC has generally been pretty accurate in my rifle, even for ball ammo. I'd wager if you can't shoot a respectable group with it, your barrel just doesn't like the 77 smk.

That PMC issue with POI shift- I have experienced that with every PMC I’ve shot, from bronze to XTAC 55 to XT 62. From Federal to any of PMC is usually a pretty serious POI shift.

Anyone else experience the same?

I've shot it through six AR's and have not experienced POI shift.