I have this:
Which I just rebuilt into this:
I usually run GI mags, but I have run Pmags on occasion with no problems. Pmags fit a little tight and sometimes don't drop free, or have to really jam them in.
The only issue I have had with the adapter is when monopodding on the magazine, It really doesn't like that.
I've shot the rifle in numerous 2 gun matches. Had some issues with the rifle but none I can blame on the adapter other than the monopod thing. Works the same with the adapter or the Czech mags.