The memo I referred to (and copy was on GOAL.org last I looked) actually says both guns and mags had to be IN MA ON 9/13/1994 (IIRC, "before" doesn't count). The law for both does NOT mention "in MA" in any context whatsoever. Also interestingly said memo claims it is ILLEGAL for ANY MA DEALER to transfer ANY pre-ban large-cap mags or pre-ban so-called AWs. It is right there in the 3rd paragraph of said memo!! So basically, they should be prosecuting all MA Dealers if they actually believed the drivel they wrote in that memo!
Here's the verbatim quote (3rd para):
You will notice the absence of any words explaining that this means "made after 9/13/1994 ONLY" in the above verbatim text of this infamous letter (and the magic date IS stated in the above-referenced clause 16 as passed by the legislature). NOT AN ACCIDENTAL OMISSION!
As for mags, almost all that I bought were at gun shows, no receipt given in most cases but certainly didn't have my name on any receipt and most don't put the date on it either!