i bought some gen 2 tapco mags just to have a few more extras love p mags but have absolutely no problem with the new gen tapcos either and they are a couple bucks cheaper
Another +1 for Lancer L5 mags. They have steel feed lips and are translucent. AIM Surplus has them in stock for $19/ea, but I'm sure you can find them cheaper if you hunt around.
6 Brownells metal GI type, 1 Lancer, a factory Bushmaster that needs a green follower, and a single 20rd GI mag lol. Thinking about getting a few Pmags but it just doesnt look that great in my A1 but function rules over looks IMO. Regardless I need more mags lol
My first lower was made by a company called Essential Arms. They fit GI steel mags just fine but Pmags would not go. I couldn't even get them to fit halfway through the mag well. All other manufactures I've bought since then haven't had any issue (DPMS, Rock River, Sun Devil). So I just took it as being a manufacturing tolerance defect with Essential Arms.
You can also try use some sand paper to the PMags to get them to drop free. There is a post on arfcom with pictures for guidance. Google "sand pmag" and it should be the first search result.
Just to note, I have not tried this myself so I cannot confirm that it will work.
As others have said, LOVE the P-Mags, I've also got about 2 dozen Israeli Oralite mags, used to be able to pick them up through Shotgun News for like $6 a pop, can't find them nowadays though