Anderson Lower / Best mags

Hey so for the homies with a poverty poney lower - I have a couple p mags and they won’t drop free. I tried Lancer which fits and falls free but I need to smack the hell out of it with a closed bolt. 1 steel mag works perfectly - Are the old school metal mags the way to go ? If something’s working for please leave a comment I need a few and don’t want to waste money experimenting. Thanks,