Most plastic mags actually have a date stamp which might melt when out on a camping trip.From what the gun shop told me is that you can't buy the completed magazine so they don't stock them. The same store had a 55 gallon drum of "parts" so you can assemble your own as the older ones were grandfathered in.
How stupid? The mags don't have SN on them. Who is to know if they are new or grandfathered?