yep, I don't think any of mine will freely drop a pmag.I have Noveske, Sonju Defense & RRA.
I have a Sonju that drops PMags great. Funny how there's so much variation.
Damn my JP and DPMS don't have no problems with that. How do you fix it?
Best just to use mags that drop free. If the metal ones don't, you can relieve the mag a little bit.
Also check the mag catch to make sure that's not the problem instead!