Ok, so if I find a CMI mag, that says "CMI" only on the back, it is likely pre-1994.
Any LEO, Springfield, or Armalite stamped sides, and anything on the floorplate would be Post-Ban.
NO. The mags after 2006 are stamped with ONLY the CMI on the back of the tube. BUT, at some point After about 2007 or 2008 (not sure when) then both the tube and floorplate are marked.
As I MEant to say aboe, from my observations, the 2006 are UNMARKED but the ones after that are marked with CMI only. I have a bunch of both.
I don't think there is any way you can PROVE a CMI mag is pre-1994 ban.
So this is what I KNOW based on MY experience:
2006: Unmarked at all
sometime 2007 and after: Marked CMI on back of tube only, blank floorplate.
Sometime between maybe 2008 or 2009, when the 25 round mags came out, the floorplates were/are Also marked.
But as has been the case before, Different is the man to say so with proper authority.