I've got 2x G&P Bakelite mags on the way, so I can answer your question when they arrive.
So far, I've put the stock CYMA mag through it, and it works flawlessly- also, I bought two metal standard TM AK mags and they both work great. One had misfeeding problems at the beginning (due to the mag being old), but it randomly stopped after firing two mags through it. One can only assume all TM mags will feed flawlessly, now. No wobble, all the mags I've tried fit perfectly and snugly.
Age verifier- Halifax region