not sure
I thought that was what made a MA compliant gun(necessary if made after certain date, might've had to show color on indicator), I could be wrong. Just thought I read it somewhere, didn't stick because I don't reside there. I know Glock is buying back a lot of gov't issued 9mm's so they can upgrade to .40 at a deep discount. Glock was intending to polish up the 9's and sell them in states they were not allowed to before. These older gen 3's were made before whatever date and only required chamber indicator which all glocks have, just not painted red or orange or whatever the magical safe color is.