I have had a half dozen local city PD issue boxes from 2011 to 2015 and the box end label has exactly the same month/day/year as the silly included case from test fire.
Yes, 2011-2015 is newer than the guns we are discussing currently, but still more data for the discussion.
Btw, maybe also relevant that 2012 was still showing the four digit number with first digit representing a year and last three representing a Julian date, but by 2014 the four digit code has been dropped and replaced with a 6-digit number that is actually a "typical" date, such as one I am looking at now that says 081815, which is Aug 18, 2015