Being a Marylander, I was looking for some 30 rd Pmags. Turns out that the only place that I called that had them was Shooters Supply in Hanover.
Mike, the owner is a great guy and he showed me around with his vintage and modern collection. Very knowledgeable guy. I will go back there when in the area.
There is also the trading post, which is a Pawn/Gun shop in Gettysburg right on Rt30 1 mile off of Rt15. Very easy to get to. They carry 39rnd Pmags. Call and ask for Shawn, he will even order the color you want prior to you gettin there, more than likely. Very easy to work with # 717 334-3979. Tell him the Walmart Vendor sent ya!!
Yes, I second that about Mike at Shooter Supply. I have been dealing with him for about a year now. Nice guy, very knowledgeable. Definitely recommend you give him a try.