Just in case you get older PMags:
My PMags from Nov '08 had a problem dropping from several magwells. If you use a fine millfile on the front edge of the PMag where the left/right halves are welded together... that weld has just the slightest raised lip that drags on the front of the well. If I had to buy more PMags that I knew were from a 'problem' production run - I'd snap them up and do a little filing. Easy.
Feb '09 PMags are sweet for me.
YMMV, works for me.