Took the two new mags out and loaded each with 15 then 10.  I used (15rds) 124grn unsuppressed and then (10rds) 115grn suppressed.  I fired these through the 9KT.

Then loaded up 15 in each mag and shot the 9CT suppressed.

No issues at all with any of the mags with either PTR.

Both the 30 rounders I got lock into my POF MP-5 and don't wiggle. So far so good.

I got in a couple of the PTR mp5k clones.  Mag wells are on the snug side with metal magazines.  They're extra snug with the ETS and these AC unity magazines.

I had them out yesterday with the 30 and 40rd ACUnity mags.  Neither one of them ran well in them.  The 40rd mostly worked, but having the mag in the gun caused occasional ejection/extraction issues.  And the 30rd, for some reason in both guns it would chamber a round when you dropped the bolt, but when you pulled the trigger, it would click instead of bang.  I figured maybe the mag somehow rubbing on the bottom of the bolt and screwing with it.

Both guns ran 100% with POF, HK, and KCI metal mags.

Did you ever find a fix for this?
I took 2 new AC mags out with me today and every other round was failure to feed with both mags. At least the fit the mag well nice.

First round would chamber, fire, extract normal. When the bolt picked up another round it wouldn't chamber correctly, round would be stuck at a 45° between the bolt & chamber.
Any ideas? New to the platform (PTR ct9).  It ran perfect with the mags that came with it, don't remember the name but are clear, feel cheap.