Just got in some D&H 30-rd mags and they also have a date stamp. Very nicely finished y the way. Widener's still has some mags in stock from $22-$30. So I know first hand that NHMTG, D&H, and since being pointed out to me, PMags as well all have date stamps.
My older (pre-2008) C-Products mags do not have a date stamp but I don't know about more recent production.
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